Thumper Club Forum
Technical => Bike Problems/Questions => Topic started by: leah on June 16, 2010, 10:25:09 AM
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Well, after another evening of trying but not succeeding in starting the SRX 600 I've been rebuilding I'm moving to this area of the forum as it's definately turning into a problem...
The bike came to me as an unfinished project - rolling chassis with engine installed. Both engine covers were off, rocker cover was off, there were no carbs or exhaust. I sourced the various bits required including a set of ancient carbs off a breaker, new fuel taps & hoses & a reasonable second hand exhaust.
I spent a long time cleaning the carbs ultrasonically & soaked them in coke- see my thread in Project Progress- the choke mechanism was well & truly siezed but I freed it off & I think the carbs are as clean as they're ever gonna get. The float height is correct, the pilot screw 2 three quarter turns out, & as far as I know all other settings OK...
Exhaust on but not entirely tight as it's all coming off again for paint. Electrics seem to be working, I have a spark which I checked by leaving the standard plug in situ & putting a spare on the cap. Trouble is I don't know what constitutes a good spark. It doesn't seem as blue or fat as ones off my other bikes (LC's) but it is there.
The bike has run briefly last week. I did a lot of kicking, bike did a lot of backfiring but did start. It wouldn't tick over though & I struggled to re-start it. Eventually I did that night but it was late by then & I didn't want to upset the neighbours so I let it die again without managing to get a tickover. Since then I've attempted to start it several times, first without choke as ambient temp is warm & my old Honda CB350 is starting without choke at the moment, but then with half & full. Been trying all the tricks i've read about on these pages such as finding TDC, kicking over without ignition on, priming the carb etc.
Last night I decided to check decomp cable adjustment so removed timing caps to get TDC on compression stroke. Here's what I call a funny thing- should there be oil on the generator side? I've had oil leaks all over the place since i filled up, including two of the side cover bolts which I found out needed O rings. I think these are meant to be wet as am I right in thinking they feed the oil cooler if it's fitted? It isn't on mine... Thought id cured all the leaks & I've never known a bike run a wet generator ??? ??? But the fact there's a gasket on the cover & O rings on the two plugs indicate that maybe this is right. I don't think it's awash but having kicked the engine over with the timing plugs out oil was thrown out of the openings. Have I missed an O ring somewhere?
Would oil all over the flywheel affect starting? It's CDI ignition so I don't know...
I need to get this bike running as I've spent so much time & effort & money on it. I've had more kick start bikes than electric so i didn't think this one would be a problem. OK, a 600cc 4 stroke single is a different kettle of fish to my LC's but I did manage to start my exe's 750 Bonnie which doesn't have decomp. I don't think I'm too wimpy...help :(
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The oil in the alternator is correct, with the exception of a Morini and two strokes, all of my bikes have a had a wet alternator.
The SRX ignition system does not rely on the battery, it uses a coil in the alternator to power the ignition system. The will be fairly weak when kicking it over so don't expect a bug fat spark.
If its wont tickover then I would suspect carburation or an air leak, what are the carb rubbers like are they well bonded to the aluminium core ?
Did the previous owner tell you why the rocker cover and side covers were off ? Is the valve timing correct ? Have you removed the head to inspect the valves ?
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Reassuring about the oil in alternator side, thanks Steve. As to why engine covers were off I would guess they went for polishing & didn't get re-fitted. I checked the valve timing & clearances & they seemed spot on. The carb rubbers look OK to me with no obvious splitting or cracks...i'll tighten everything up a bit more to see if that helps.
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...i'll tighten everything up a bit more to see if that helps.
You will need one of these:
(http://farm4.static.flickr.com/3546/3428652544_76e0db2fc4.jpg)
;)
GC
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All guess work from here...
If it will start, not tick over and then does not start for a while, difficult to start etc (it could be my lawn mower) I would guess that everything is a little marginal and we need perfect luck to get running.
It has all been cleaned and re-built.
Check the ign and valve timing again, and then again. Really question what you have and what you should have - thus speaks the man who more than once has checked and made the same mistake and had the timing set for full advance when it should be retarded etc - and this is a real bugger. Mind a friend with a Brit single managed to get the gizmo back together 180° out - looked perfect except it was firing on the exhaust stroke....
I would try taking the plug out and cranking it over wih the fuel OFF and the throttle wide open. Try and see if there is an excess of fuel. Does it stink of petrol, possibly stale petrol? Is the plug wet, oily? Give it a damn good clean. Heat it in a gas flame (or electric) before putting it back - a nice hot plug sometimes seems easier to get a bike started with. Tip about a thimblefull of petrol into the pot through the plug hole (if you can) - I have used a small syringe and a long tube in the past for hard to reach holes - and with the ignition on and fuel off try starting it - it may burst into life and die (sound familiar) running on the fuel w have dumped in (it may not). If it does kick into life for a moment or two we know we have a electric pixies in there and it will run.
If it does not work try it a few times - it can be that the beast throws all the fuel out or the fuel floods the plug and kills the spark.
My guess is it will kick up and run for about 2 seconds.
At this point I have to admit I have no idea about the fuel tap etc on the SRX, it may be a vac tap in which case you may need to clamp the fuel line to 'switch off the fuel'.
If that works - or start here - try starting the bike with the fuel on and a nice clean, hot, plug in place. Having cranked it over half a dozen times with the plug out, throttle wide open and ign off - to remove any residual fuel in pot.
If it runs up and dies, then quickly check the plug. Is it wet or dry? - have to be quick as the petrol evaporates if it is there.
If it is wet or really sooty it would suggest that the carb is flowing too much fuel - stuck float needle? etc If it is bone dry and no sooting it would suggest that not enough is getting there. In either case it would be a recheck the carb settings and if no luck a restrip of the beauties...
Steve has mentioned an air leak, you have mentioned the exhaust mat not be sealed fully. Can you wrap some cling film around the carb mount and stub etc - make sure there is no leak between the carb and the pot (it will melt but will seal things off for a bit) as for the exhaust, if he engine is feeling marginal a leaky exhaust will cause problems, a fine fettle engine will run with none attached - make sure the pot/exaust is sealed - more important than the pipe/silencer joint.
Probably all things you have tried, but remember that 4-strokes are the devils own creation and that the LCs you have had are actually the charriots of the gods. 4S singles are as close as the devil manages to a real engine (actually a nice twin come close) but they are designed to frustrate, where as 2S, especially Yamaha water cooled 2S are designed to make you fall in love each time you start them, pox on the environment!!!! (OK apart from being clean shaven I am a beardie greenie - but just love 2S)
With luck the above will help - even if it only to inspire someone with an SRX to write - IGNORE HIM, It is XXXXXXXX.
Come on guys I am flying blind here.
R
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Aye leah,
Sounds a right scunner! ???
The petrol tap under the tank as you probably know is just a tap, 'ON' or 'OFF'. The tap on the near side of the frame is a vacuum tap, 'ON', 'PRIME' and 'RESERVE'. Have you connected a pipe from the top spigot of this tap to the small brass spigot on inlet side of the 'carb' manifold? If not, do so! To 'prime' the float bowl of the carb, turn the tap to prime and petrol should flow into the float bowl and then be stopped by the float needle seating as the float rises. There should be sufficient petrol in the carb to enable the bike to start or 'flood' it! If the bike starts, runs a short while and then splutters, suspect the petrol tank breather is blocked! :( Clean the breather then try again. Once the carb is primed, the vacuum tap can be left in the 'ON' position.
Starting Sally from 'cold', even with warm ambient temperatures, requires full choke, take the engine through 2 TDC compressions (no need to thrash about, just turn the motor over!), ease over TDC for the 2nd time, allow kickstart to return to the top of the stroke, turn on ignition and swing the kickstart through the full arc. Sally usually starts and settles to a fast idle ~2000rpm. If not, take over TDC once then swing through again. If no response, shut the choke fully and try taking over TDC and then the swing through again. This usually results in at least a splutter or cough, which partially clears the unburnt fuel and the full choke maybe applied again. DON'T TWIDDLE THE THROTTLE OPEN AND CLOSED, WHILST DOING THIS, LEAVE IT SHUT UNTIL THE MOTOR FIRES AND RUNS ON THE CHOKE! :)
Check the thin orange wire from the coil beneath the front of the tank, for fracturing of the insulation close to the body of the coil. Sally's was fractured and the wires covered in verdigris! ??? Required cleaning and then encapsulating in slow setting Araldite. Clean ALL the earth connections to the frame, check for continuity, between wire, tab/connector and frame. Lightly 'Vaseline' or ACF50 after assembly to keep watertight and prevent corrosion. Check the wire from the coil to the spark plug for fractures as well. Buy a new plug cap (NGK XD05F) <'NGK_parts_catalogue'> (http://www.ngkpartfinder.co.uk/partfinder.php) and ensure a clean tight fit onto the wire from the coil. Check ALL the connections from the alternator, back to the CDI unit, clean, waterproof them ALL!
Do you have a manual? If not, send me a PM and I will send a CD-ROM to you.
Have you used the diagrams from SteveH's www site? Here: <'Wiring_1'> (http://www.srx600.f2s.com/srx600/plist/partslist.php?image=images/plst_d40.jpg&texturl=list/plst_t40.htm&heading=Parts List - Electrical 1)
If 'Sweetheart'! ::) still proves reluctant, do you have good compression? At least 120psi, but better if you can achieve 150psi +. I know they will run on less, but loss of compression also means oiling up and all manner of other nasties are possible and we don't need that at the moment. Hopefully, removing the corrosion from the wiring and any blockages in the breathers will suffice.
Please keep us posted.
My regards, Bill.
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Thanks Bill
Much more use than my blathering from a position of ignorance
R
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Aye Rog,
You, blethering, never! ;) Havering, maybe! ;)
Ciao, Bill.
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Many many thanks for your comprehensive advice & suggestions, all of you. I'll be following the advice & will let you know how I get on. Thanks for taking the time to impart your extensive knowledge & experience. Really hope to meet you for a rally with a running SRX :D
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Hi leah,
I bought an srx 400 that had been off the road for 10 years. paid someone to clean the varnish out of the carbs only to find it would still not run, turned out they failed to get the gunk out of the pilot jet. I bought a new one fitted it, it took for ever to start then, wouldn't run, back firing when trying to start. I found that the setting for the pilot screw was critical. Same with the srx 600. I am only 8 stone and to start with I really struggled with starting the 600, I would get it going then at a petrol station it would not start.
An 1/8th of a turn on the pilot screw can make all the difference. if it is backfiring and not starting try turning the screw out that will richen it up a little. From cold I turn the ignition on then set the choke 1st click and then turn the engine over a couple to times to get the oil round, over tdc, kick start lever right to the top and a full kick, I always let it warm up before setting off because if it stalls it can then be really difficult to start again.
Good luck, regards Christine
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Hi Christine
after the first round of non-starting I took the carbs off for a really thorough cleaning & I did spot that the pilot jet was blocked. It's a very small hole but I eventually cleared it with an acupuncture needle (stainless steel 26 guage is extremely fine & ideal for these jobs even tho you "shouldn't put anything solid down a brass jet").
Thought i'd found the problem especially when Rex did start & run. This was on 2 + quarter turns out on pilot screw. Since then I can't start the bike & have tried 2 + 3 quarter turns as standard, & 2 + half turns out - no joy. On looking at it last night the LH carb seems to be seeping oily petrol from somewhere near the top, above the float bowl & choke cable area anyway. Need to get the tank off to investigate this leak anyway so...
Good luck with your sticky clutch. Chain not too tight or loose is it? I've found baggy chains can affect getting neutral :(
Cheers Leah
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Hi Leah,
I found that even though I was careful cleaning the pilot jet it still got slightly larger also if I remember rightly it has really tiny holes down the sides. While I had the carbs apart I changed all the '0' rings but not the choke plunger (because it is very expensive) NRP are good for getting carb bits and a fraction of the price of gen yam bits. They can find you an 'O' ring that will fit the choke plunger and also have the vacume fuel tap bits.
Once you get the bike running if the pilot jet is correct when you turn the pilot screw right in it should stall the engine, if the jet is too big it will keep running. I am no expert just going on trial and mainly error, I took the carbs apart so many times on the 400 I could almost do it with my eyes closed. I was lucky in that there were no other faults just carb problems.
Christine
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I see the problem now...........!
You've called the bike REX!
Bikes are of the feminine gender
Renaming will provide an instant fix.....
I suggest a Thumper Club poll for a suitable name ;D
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How about Roxette?
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Rexanne?
To be sung in a bad French accent ala the British Intelligence officer in 'Ello 'Ello
"Rexanne you dot av to put on de rod lite... etc"
Sorry Sting please do not sue us.
R
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He remains Rex cos he WILL be king!! Not yet tho as I'm still struggling: another carb clean with new main & pilot jet plus all the other goodies you get in a carb refurb kit. Float height checked and fuel definately getting to plug (backfires indicate that fuel getting thru no?) Then there's the new coil, plug cap & iridium plug. Nothing except backfiring so I now checking valve clearances & decomp cable adjustment as per the manual. Thing is when I get the T mark aligning with the pointer it wont stay there, just flips round a bit. The only way to keep it there is by physically holding the spanner turning the crank. Is this right? Is the timing a bit out? I'm lost here as other bikes I work on are 2 stroke twins where TDC can be found and the crank stays put! The plug is out on Rex incidentally so there's no compression fighting the piston.
interested in any coimments and help here & realise I'm probably being dense... :-[
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Aye leah,
Reads as though the timing is 'out'!
To make things easier, put a piece of 6mm rod through the hollow back axle and raise the back end on two axle stands, or else use a paddock stand. Engage 2nd or 3rd gear and turn the engine over using the rear wheel, checking until you reach the desired 'T' mark with the piston and cam in the correct positions. BE CAREFUL THAT YOU ARE NOT 180 degrees OUT! ??? ??? ??? You can then lock the back wheel in position by applying the rear brake and tying it down! You will still have backlash in the gearbox and primary drive to contend with, but it won't 'flip' past the 'T' mark, as at present.
Others may have better ways of doing it than me, and if SteveH or SteveL come along and offer a method different from mine, which appears easier, USE IT! 8) 8)
I hope REX will soon run and perform, rather than remaining as a petulant brat!
May perseverance prevail.
My regards, Bill.
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Hi Bill, thanks very much. Don't see why your method shouldn't work as the back brake works at least! Just to make sure I've got my 4 stroke cycles right, the compression stroke is the upward one compressing the fuel/air that came in on the intake stroke. Therefore on this stroke all valves closed right? If 180° out some valves would be open & you wouldn't be able to check clearances as there wouldn't be any?
So for clearance checking the flywheel must be dead on that mark? If the valve timing was out, how would I know? I didn't assemble the head and valvegear as it was already on. Got a horrible feeling I need to remove the LH engine cover to check camchain marks... :(
Anyway I'll have a look tonight.
Regards
Leah
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what i do is..........take the plug out, stick a pencil down the 'ole, (a long pencil, so's when/if you let it go it won't disappear!)
turn the engine over slowly until the pencil tells you you are at TDC, then check valve clearance, if there is clearance on all 4 valves you are at TDC on the compression stroke, no clearance?...turn it over one more 360deg, check clearances again.....if you still havn't got any clearance then you have an issue with the cam/chain positioning..... the clearances i use are 3 thou inlet, 6 thou exhaust...a sort of midway setting.
in my experience (i am using high comp pistons, not sure if this is true for standard comp) if the timing is out by a tooth or 2 on the camwheel, then you'll feel the piston touch the valves........
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and another thing......
I do have a carb you can borrow......it's a single 42mm dellorto with accelerator pump, on a handbuilt manifold....the main thing is....it works......was on my srx6 for several years........until i got a matched pair of 36 mm dellorto's off fleabay which fit original inlet pipes.
you won't be able to use this on the road...'cos you have to bash 10 bells out of the base of your tank to make clearance....BUT....with a plastic bottle and pipe tied to the cross bar (with your tank removed) then it'll work fine....no choke.....blipping the throttle pumps xtra fuel in.
not only that.....
I have l/h cover with generator coils and ignition pickup
you are welcome to borrow both to try and resolve this problem.
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thinking about it.....
I sold one srx6 i'd built... to a plumber friend of mine....at half price.....and got a full central heating system fitted (no i'm not suggesting you flog rex to a plumber :D )
but......after about 20k miles he decided to strip it all down and 'tart' it up a bit...all was fine and he completed another 10k miles then started to experience difficult starting....and finally...no starting....
he bought it over to me in his van and i went through everything.....got it rebored, nice new h/c piston, got new valve seats fitted, rebuilt it and set the timing up......and the bu55er still wouldn't start....odd backfire (it was running on a pair of mikuni 34mm carbs, which i tried on my bike just to make sure they were working) a few pops and wheezes....all this time i was checking that i had a spark....
i ended up sending the generator away for testing (normal resistance testing showed it to be ok) it proved to be a winding breaking down (the high voltage tester is called a 'wee megga', i know you were just dying to know that)....once repaired....also got a new pick up, everything then became wonderful!
just a thought
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Aye leah,
I am sorry for the delay in replying and my thanks to SteveL for stepping into the breach.
"Just to make sure I've got my 4 stroke cycles right, the compression stroke is the upward one compressing the fuel/air that came in on the intake stroke. Therefore on this stroke all valves closed right?" YES
"If 180° out some valves would be open & you wouldn't be able to check the open valve's clearances as there wouldn't be any?" YES
If the cam/valve timing is out by 180deg, the valves won't touch the piston, but the spark will arrive with no compression on the inlet or exhaust stroke! ???
As SteveL says "if the timing is out by a tooth or 2 on the camwheel, then you'll feel the piston touch the valves........" ??? But I don't think that is your problem or else the engine wouldn't have turned over/ you'd 'ave heard a 'dink', as valves touched piston! ???
Before you strip bits of engine cover off, are you sure that the electrickery bits are all 100%???????? I will send the 'Ignition' section from the Yamaha workshop manual, by mail attachment, for you to use.
Sorry not to be of more help and I hope others will help if they can. Or 'SHOUT' if I have made an error!
My regards, Bill.
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Aye leah and Steve,
That last post of Steve's is where my head is going as well, as you can see from my immediate previous post about circuit diagrams. Will still send pdf under separate post.
Regards, Bill.
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Thanks again guys. Bill - I got the ignition info so will attempt to check the generator out.
Steve, many thanks for the offer of carb and generator. If I can't resolve this problem I would be glad to borrow them...just can't believe this is being such a hassle :o
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Unsure about pilot jet and pilot screw details. Pilot jet has a hole through it and goes in snug. Pilot screw needs to be backed out a certain number of turns. My pilot screw was backed out 1 3/4 turns when I got the bike and thats where I set it after the carbs were completely cleaned and re-assembled. It started on the second kick and ran fine but I don't know anyone with an SRX 400 to ask questions of so I'm kind of running blind. Any info on the pilot screw and how to reach it would be appreciated. I'm up in northwestern British Columbia, Canada and most people don't know what make or model my bike is. Love this site, love those thumpers.