yam advice please! -ignore if my threads are p'ssin you off!!-

[andy230]

hello again,

I received from Mr Yamaha today 6 washers, 2 spacers, and 2 rubber seals.  The cost was awful; suffice to say "a good night out". However, they're important, so genuine Yamaha is was to be.

I went into the solar shed to begin putting it together to check squish and valve clearances.

Noticed that one of the studs I had to replace was shorter than the others; it became evident which one and why when I placed the 3AJ barrel onto the new studs.  You cant get the RH rear nut on unless this stud is in the correct the position... Are you getting me, SRX afficionados??

I went to put the 98mm wiseco piston on.  Hmmmm.  No circlips,    so I thought about re-using the ones from the omega 100mm piston.  Just to get the piston on, to allow the head to bolt down etc.  Grrrr   the omega ones dont fit the wiseco piston.

I gave up, and started packing everything into the boxes I got them in.... Ah! There's the little packet with the circlips     so thats tomorrow night then!

However (finally, thru my verbal diarrhoea) we get to my questions:

1) any tips on getting circlips in and out?  There is a single notch on the wiseco (as opposed to 2 notches on the omega).  Do we push the circlip round till the open end is in this little cut-out, and then lever out carefully??  i've always considered myself to be a wee bit ham-fisted, and end up marking the piston (only very slightly, and not anywhere near the rubbing surface).

2) what about in?  Gentle persuasion?  Where should the "gap" of the circlip be in relation to the notch.  Not right at it, I take it?  So does one tap it round??

3) and reading the little wiseco insert papers, I'll be needing to check the ring gap.  Not done it yet, but am I likely to need to open the ring gap out??  Any info/ advice?  I'll probably do this over the weekend


More and more I am thinking about giving the motor to Martin Sweet to put together.  However, this  feels like a terrible cop-out.  And quite against my tight-as-fuck principles.  I think it would be a couple of hundred quid in labour (no parts to buy).  Confidence is low!  (Althought the head job I did one the 620 was slow and steady, but didn't leak any oil, and did run very well.  You guys all talked me thru that one too!!

However engine failures are expensive, especially as they tend to wreck stuff as well.....

More head scratching!

Off to bed for angst-ridden, turmoiled sleep.  We are also running out of time!   Arrrrgh!!

[themoudie]

Oh! Whilst not being a very good example, with temperatures falling to -6c already, I have not entered the workshop tonight!

However, I use 2 sharpened minature screwdrivers (5mm blade width max) with plastic handles to extract and fit circlips from the end of the gudgeon pin recess on Sally and the Duke. Stuff the crankcase 'gob' full of clean [CLEAN] rag with the piston at or approaching BDC. This should immobilise the assembly and allow carefull pleacement of a blade at the end of the circlip with the other end being inserted in the small cutaway to lift the circlip from the groove and then progressivly lift the circlip out. The first blade prevents the whole circlip being chased endlessly around its groove. Once fitted ensure the ends of the circlip are away from the groove and that there are no pieces of aluminium swarf, however small, left lying about.

Check ring gap afore putting rings onto piston. Liberally oil the cylinder bore and ring then insert a ring into top of the bore, making sure the 'TOP' land of the ring is to the top of the bore [ I assume that the bore has been rebored and or honed to remove any lip at the top end of the liner]. Then using the inverted piston move the piston down the bore 10mm so that it is square [IT MUST BE SQUARE] with the bore and then measure the end gap with feeler guages. Remove the ring from the bore and then clamp the ring between 2 pieces of 6mm ply in a vice with just sufficient end of the ring showing to remove a little metal from the end of the ring using a fine cut, broad 'needle' file. Wash ring with brake cleaner and then repeat until the end gap is to specified clearance. Repeat proccess for all rings.

THIS MAYTAKE A WHOLE EVENING!!!!!!!! DO NOT RUSH OR CUT CORNERS. KEEP RINGS SQUARE IN THE BORE, REMOVE ALL FILINGS AND LUBRICATE EVERYTIME YOU REFIT THEM IN THE BORE.

Once you have all the rings correctly gapped, you can then fit the piston to the rod, fit circlips and then with rags still in place fit rings to piston with plenty of oil and use strips of thin plastic to facilitate sliding them over the upper ring grooves into their correct position [TOP ring lands are facing the top of the piston]. Finally before sliding the barrel over the piston, space the ring gaps at ~120 degrees around the circumference of the bore avoiding alignment with the valves or gudgeon pin. Put the cylinder base gasket, with [sparingly] or without 'goop' in place. Ease the barrel over the piston and rings and then remove the rag stuffing from the crankcase gob before seating barrel on gasket.

My apologies to all of you whom this may be like teaching their mother how to suck eggs!

I hope she's a good motor Andy and take your time!

My regards, Bill.

[OMEGAMAN]

"A good night out"     for a scot, that's about £2.75,       so what are you moaning about?   

[Steve Lake]

Bill just about has it spot on, of the 7 srx's i've rebuilt none have needed the rings gapped, so you might get lucky.

When removing the circlips move the clip round in the groove until the gap is, say, 15 to 20% passed the notch on the piston, then with the screwdrivers Bill mentioned you can carefully lever  a 3rd of the ring up and out of the groove in one go, enough to be able to get hold of it with needle nose pliers and pull the rest of the bu55er out.....normally without marking the piston and no swarf.

Have confidence my man......you can do it......very reassuring...when on the 1 mile Norwich straight at snetterton, 8k+ on the clock in top, to know that YOU assembled every last little bit, so it MUST be alright.....keep that in mind as you torque up your nuts (and the bikes) and check all your clearances... pip pip

[Steve H]

More and more I am thinking about giving the motor to Martin Sweet to put together.  However, this  feels like a terrible cop-out.  And quite against my tight-as-f*** principles.  I think it would be a couple of hundred quid in labour (no parts to buy).  Confidence is low! 

You will learn very little if you pay someone else to do the job. Just be methodical and dont rush.

[mini-thumper]

I'll do you a swop Andy. My garage floor is knee deep in chassis parts and almost everything needs something doing to it, even if most of them are fairly minor. I'm hoping to get it back on its wheel in the very near future. We can then arrange to meet in a lay-by near Luton to shoehorn the two together!

This commercial break is brought to you by Swarfega.

Boyd

 

[andy230]

I'll repeat it:  I LOVE THIS CLUB !!!      Thanks guys....

Ok, replies: 

John: Shut it!      I'm just careful!  See you soon with a motor matey.  Sorry just whistling down the M6, but it was a long day, so I just kept trucking.  Plus the motor is still in the frame!

Boyd:  How much did Swarfega give us?!

SteveH:  A nights sleep strengthened my resolve.  Agreed, I will just do it slowly.

SteveL: Thanks for the encouragement and tips. I'm not too far wrong I think!  Frame for you soon too!

Bill: You're a diamond.  Thanks a lot for this step-by-step, better-than-Haynes approach.  Much appreciated.  When 19/20, I did the 650 Dommi (norton) motor, but my old boy is toolmaker, so (little did I know it at the time!) he was I am sure, heavily supervising!  And I've had the head & barrel off that, and done the head on the commando motor.  But brit stuff is different, isn't it??!!  You know there are no torque settings for the Norton heads??  Mick Hemmings reckons "as tight as you can get it"  !!!!  (cast iron barrel tho).  Different world eh?

I had a look inside my original 608 SRX motor, but stripping isn't the same as building!

And then the head on the SRX didn't involve piston removal, gapping rings, checking clearances etc.

Thanks again guys for holding my hand up the steep bit of the learning curve!

cheers for now

andy

[guest27]

I may have missed something but you do not need to put the circlips in to do the squish etc - they stoop the pin rubbing the cyliner to oblivion at speed.

Have not used them myself but I understand that the PTFE buttons are popular for engines pulled apart regulaly - is this still so?

Terry Hobbs used to recon that the correct torque for an iron head / cylinder was pull it down untill the threads strip or the stud shears off and then ease it back a bit.. mind there was a lot of added colourful language in there too.

CHeque will be in the post soon Andy - infact if I can find a pen I will write it now.

R

[andy230]

I may have missed something but you do not need to put the circlips in to do the squish etc - they stoop the pin rubbing the cyliner to oblivion at speed.

R

Hiya Rog,

Surely the circlips need only be *just* in (ie even the ill-fitting omega ones would do) to do the squish and valve-piston clearances.  Cos its not going to be at speed is it??  I was planning on turning the crank with a big spanner, and only a single valve spring etc...

(Although I may just keep the head assembled as is to save stripping it just to take a spring out.  HArder to turn over I know, but I'll use a longer bar...)

Surely I cannot run the motor (ie "at speed") till the clearances are done?

a






And thanks for the cheque!

[Steve H]

Andy, if you have to take the piston off again to machine it etc, you will have to replace the clips as they shouldnt be re-used (even if engine has not run).
Take the outer valve springs off, remember dont rush and dont take short cuts.

[andy230]

Andy, if you have to take the piston off again to machine it etc, you will have to replace the clips as they shouldnt be re-used (even if engine has not run).

Cheers steve, didn't know that...  I'll get Wiseco one's, they're probably specific.

Take the outer valve springs off, remember dont rush and dont take short cuts.

ok... thats a job for the weekend.  Why not just leave it as is.  Harder to turn I know, but saves stripping the head??

a

[themoudie]

Aye Andy,

As Rog and the two Steves say, there is no need to assemble with the gudgeon pin circlips, PROVIDED you are only doing a 'fitting' assembly. You are only going to revolve the engine with your hands and usually gudgeon pins are an interference fit in the piston bosses, requiring heat to enable you to remove the pin. Same idea with only using the inner valve springs, you're only holding everything in situ and measuring the clearances and then adjusting those clearances to specifications either supplied by the manufacturer, calculated by you, or derived from experience i.e. ring end gap left to tight and under thermal expansion the ring seized in the bore at 8K down the Norwich.

Yes, you may pay a tuner what appears to be a lot of money, but you are buying his experience, patience and time and as we all know plumbers aren't cheap! £75-00 an hour up here and no guarantee:o

[My apologies to the few remaining honest tradesmen, rather than the garish van 'artistes' who are proliferating like copulating fruit flies after a 2.5 day 'working' week with lager lunches. ]

As for being a diamond? NO. All of us can get it wrong and as this demonstrates, I didn't think to write about the 'fitting', rather than the final assembly, if you ken? Be methodical and chill, the calm of the workshop is a very different place from the mania of the pits between races. But you watch somebody good in the pits doing a good rebuild for Sunday, because the motor blew on Saturday, it's another plane. It'll only get rebuilt if they have the bits and they now WHY it blew.

I wish you all the best, Bill.

[guest27]

Thanks Bill and Steve for clearing up what I thought I had said.  Andy - as you are only cracking the engine down to get the clearences set you do not need to do any of the oiltight sealing - ie dry gaskets so it comes apart no gasket goo till proper build, and you are turning by hand, so unless the valves touch the piston and you use a bloody great bar to get it over TDC - you need the minimum in there.  Inner valve springs as these tend to be the weakest, dont bother with the circlips, they are a belt and braces for the gudgeon pin, the worst that can happen if it does slide when turning it by hand is a mark in the oil inside the cylinder - it is not going to take out a gouge.

Rings need to be fitted to keep the piston in its proper place and I think you are supposed to set it with zero valve gap  - after all the piston valve clearence matters when the plot is hot not when it is cold on the bench - off at a tangent - I think some bikes are set with negative clearence - mm looks like a dial guage to me...

Leave the plug out - you want no compression - then any sudden resistence to turning over is either metal against plastacine (so easy to over come) or metal to metal - not easy to over come and we dont want too!

Watched No1 son put cheque in post yesterday - so it will probably go the the AO and you will get a couple of disks of interesting data!

Any furthur news on that Ti spec.  My friend who works with the stuff says they sell scrap into the Fe industry at about £2.50 a Kg, There is a place in the States that pays more - but there are shipping costs to be considered - they can regrade the Ti easily - and known spec back into the aero industry goes £3.50, £5 maybe more dependent on the spec and the state of the waste.

Her thought was that you would be better off looking to get a couple of quid a kilo and save the problems of finding the spec, which without a cert of conformity may actually be worthless info - unless the blocks are substantial.

R

[andy230]

cool, thanks all.

She's away for the weekend, so I am gapping the rings on the table.  Too cold outside!

Top ring was 10thou, needs to be 15-16.

Bottom 12thou.  Needs same.

Slow work, eh??

Then I'll get the outer valve springs out, build up for clearances, and let you know!

a

[andy230]

Ring gap saga;

4 thou per inch bore

98mm=3.86 "

3.85 x 4 thou = 15.4

(4 thou is "usually recommended end gap" in Wiseco accompanying paperwork. "Additional end gap may be necessary for race or high performance applications".

So I went for a tight 15.5 (3 blades) or a slack 15 (single blade).

Bottom ring *slightly bigger gap*, after a bit of reading and looking at wiseco docs online. 

whats the concensus?  Take them out to a free 16 thou? Or leave as is?

A. Graham Bell's "4-Stroke Performance Tuning" is a bible, and he reckons "mimimum ring gap per inch bore is as follows: "air-cooled, turbo, and supercharged engines 0.005in; in all other engines 0.004 in top ring and 0.003 second ring".  which goes against the greater

Would you err on slightly loose in a race (ie. getting hot) engine?

Head tomorrow, off to bed!

a