Author Topic: Fuel in the crank case srx600  (Read 2583 times)

Danxup

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Fuel in the crank case srx600
« on: August 30, 2019, 02:54:35 PM »
Fuel in the crank case .. been stood probably 4 weeks with fuel in tank and tap on prime.. running all standard stuff .  Any ideas? Its also leaking out of the oil seal on gear linkage i assumed thats just because the petrol has thinned the oil.. help me....arrrgh

Propellor

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Re: Fuel in the crank case srx600
« Reply #1 on: August 30, 2019, 03:22:14 PM »
I'm not an srx specialist or anything, but the easy route for petrol into the engine is straight down the intake. Or even from the carb into the airbox then from the airbox into the engine via breather tubes. In both cases the problem is the float valve passing.

Whatever you do make sure you drain it all and renew the whole quantity oil i'd say.
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CrazyFrog

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Re: Fuel in the crank case srx600
« Reply #2 on: August 30, 2019, 07:02:54 PM »
Ditto, no SRX specialist either, but it's a common failing of Japanese bikes of the era to not have a carb overflow, so if the float valve is sticking, the fuel will find its way into the crankcase either straight through the carb intake or through breathers as Andrew says.

My F650 did this a couple of times till I rebuilt the carbs, infact it leaked enough fuel into the crankcase to cause a hydraulic lock!
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Danxup

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Re: Fuel in the crank case srx600
« Reply #3 on: August 30, 2019, 07:51:17 PM »
Cheers . .. im bloody stuck for time more than owt .. thanks for replys

Steve Lake

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Re: Fuel in the crank case srx600
« Reply #4 on: August 30, 2019, 08:41:45 PM »
well well, i've had this happen to me on my SRX6 a while ago.....
first thing is to strip the fuel tap and get a service kit for it, not expensive...
second.... shouldn't leave in 'prime' ... this allows fuel into the carbs all the time (the whole idea of 'prime', should be set to 'on'  or 'res' ... which are opened by vacuum once the engine is running ... so 'in theory' ..  with the engine stationary the fuel will be 'off', this assumes the tap is sealing properly ... hence the service kit.
3rd.... 'in theory' the float/needle valve assembly should have stopped excess fuel overflowing into the crankcase , so this will need addressing as well.

4th ... drain drain drain  and drain again ....(oil tank, oil filter, crankcase, oil cooler (if you have one) ) ,anything to get rid of ALL the contaminated oil ....

5th ... refill with oil ... start make sure (with the bleed hole open) you have good oil flow..... let it tick over until it is hot. ... check everything works ok then a very gentle run, back home....  complete #4 again, then #5 .... this is important .... 'cos you're never going to get all the fuel/oil out and your 1st fill will certainly have contamination ... and a second oil change is a lot cheaper than a seize up.

drain IMMEDIATELY .... i left mine for a couple of weeks and the clutch plates swelled up and i had to strip it out wash everything and dry it all out.... believe me you don't want to be doing that!

Moto63

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Re: Fuel in the crank case srx600
« Reply #5 on: August 30, 2019, 08:49:25 PM »
Sounds like pretty soul destroying stuff Steve, but sound advice all the same. The joys of classic ownership eh 😢😢

themoudie

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Re: Fuel in the crank case srx600
« Reply #6 on: August 30, 2019, 10:59:04 PM »
Agree with everything SteveL has said and would emphasise the use of an additional fuel filter between the petrol feed from the tank to the fuel tap with the 'Prime', 'On' and 'Reserve' options before the carb. Also replace the float needle and check that the float needle seat and float are sound, so that they are unlikely to fail again.

Having been caught out at traffic lights, after cruising up the A9 at ~60mph, outside Newtonmore at some roadworks. Shut the throttle, cruised to a halt and promptly disappeared in a cloud of petrol vapour, as petrol spewed from the carb all over the underslung BSM exhaust; the float needle being held open by a minute particle of rust.  :o Turned the ignition off and this stopped the vacuum and shut the petrol tap. Fortunately, I didn't fill the sump etc and the machine didn't ignite!

I have recently started using Westway Lubricants motorcycle oil (10w40 semi-synthetic for the SRX's and Honda Bros) and so far have not had any problems; the prices are very reasonable, especially if you buy the 20 litre drum.  ;)

Link to Westway Lubricants eBay shop: Westway_Lubricants_eBay_shop

Link to Yambits for SRX600 1986-1991 float needle/seat kit: Yambits_srx600-carb-float-valve

You may prefer to use Fowlers of Bristol for the genuine parts and their website and service are very good.

Link: Fowlers_SRX600_fuel_tank_includes_taps_parts_list

Link to the carburettor parts list as well: Fowlers_SRX600_carburettor_parts_list

Hope this helps you to get the old baggage up and running again. If there is anything that you don't understand, ask!

My regards, Bill
« Last Edit: August 30, 2019, 11:05:01 PM by themoudie »

Danxup

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Re: Fuel in the crank case srx600
« Reply #7 on: August 31, 2019, 03:04:35 AM »
Cheers chaps.. mum watched the baby long enough for me to remove the tank lastnight.  To be fair i think most of the fuel that was in it is now in the crank case and on the garage floor . Also the fuel tap was on run not prime .. should i still over haul the tap? Or does this suggest the problem lies with the carb?  Thankyou so much  for all the sound advice..  knowing my luck the clutch plates will be swollen and all the lot .. bloody hell

Danxup

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Re: Fuel in the crank case srx600
« Reply #8 on: August 31, 2019, 03:25:22 AM »
Also i did fit small inline filters between tank and tap some timee ago on bills advice.  Gonna drain out the crank case and oil tank this morning but wont have time to start digging properly until sunday morning.  Its all abit upsetting. 🤢

Propellor

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Re: Fuel in the crank case srx600
« Reply #9 on: August 31, 2019, 07:03:48 AM »
You definitely need to look at the float valve. See if it's a particle in the way or wear on the taper or seat. If it's not an actual particle causing the problem there's a possibility the bike will run fine, even if the valve is slightly worn. Sometimes it's just that the amount that passes is so slight it doesn't affect the running, but will flood the float chamber if left with a constant head of fuel above it.

I suspect your fuel tap is dodgy as well, if I've understood you right. If there's an "off" position then I'd use it every time you park up.
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Propellor

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Re: Fuel in the crank case srx600
« Reply #10 on: August 31, 2019, 07:15:15 AM »
I'd rig up a test for the tap. I'd disconnect the hose to the carb and attach a longer one down to the floor into a jam jar or whatever. I'd try the tap in all its positions and see what happens in each position over a period of time. Just a thought. It's what I'd try if I suspected the tap.

Tbh I hate diaphragm taps and if I was keeping the bike I'd see if I could convert to a basic manual on/off/res tap (checking the flow rate) but that's just my own feeling.
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Danxup

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Re: Fuel in the crank case srx600
« Reply #11 on: August 31, 2019, 07:46:37 AM »
Thankyou.   Yeah the diaphragm tap seems like abit of over engineering on yamahas part.. however i like the bike to be as original as possible so i think ill just bite the bullit and overhaul it.. Hopefully get the carbs off tomorrow and have a butchers.. 🤔

Moto63

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Re: Fuel in the crank case srx600
« Reply #12 on: August 31, 2019, 08:10:43 AM »
All sounds like good sound advice to me Dan. The best of luck with it and keep us posted 🤞
Cheers..Michael

themoudie

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Re: Fuel in the crank case srx600
« Reply #13 on: August 31, 2019, 09:36:45 AM »
Morning Dan,

If fuel tap was in 'Run' position, it would suggest that there is a fault in the fuel tap, as the diaphragm should remain closed; due to their being no engine vacuum to open it.

This does not mean that there is not a particle/foreign body/wear allowing fuel to flow into the carb and then into the engine; so the float bowl needs to be dropped and the float needle, it' seat and the pivot pin all need to be inspected for wear/obstructions. Having got this far into the guts of the carbs, I would renew the float needle, it' seat, as a matter of course, even if the wear appears minimal. You don't want your wedding tackle to be flambe'!  :o :o :o

You will also note that the carburettor mountings onto the cylinder head and rubber moulded hoses leading back to the airbox can make the removal and replacement of the carbs a vexing operation!  ::)  Check for splits in the mounts to the cylinder head. If all appears sound I would recommend soaking all four inlet tract rubber mouldings in 'ArmorAll' in a plastic tub (no need to immerse, just give them a good coating), then a good massage. This will remove a load of dirt, if present and make the mouldings more pliable. Give the mouldings a wipe down and then use just a wee touch of 'ArmorAll' to act as a lubricant when reassembling.

I have persevered with the vacuum taps on both Sally (twin shock 600) and The Mono (SRX400 monoshock with XT600E engine). I just use 'Prime' for initial startup and then switch over to 'Run' when running. Because the threads were stripped in Sally's fuel tap body, I used epoxy resin to hold 2 pieces of threaded rod as studs into the tap body and then used self-locking nuts on the outside to hold the tap to the frame bracket. Whilst other taps may fit, the whole design/position of the tap makes it difficult to attach an alternative, neatly, so far as I am concerned.

Steady away and good health, Bill

Steve Lake

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Re: Fuel in the crank case srx600
« Reply #14 on: August 31, 2019, 12:36:59 PM »
wot Bill said!
I'd also fit new hoses, nice new flexible ones, unlike the rock hard bu55ers you'll be removing, make reassembly so much easier (and fuel tight)