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Author: Subject: 2 stroke crankcase vacuum
RichardK

posted on 5/4/10 at 06:52 PM Reply With Quote
2 stroke crankcase vacuum

I've gone and bought a suzuki ts125 for my lad to go on when he's 17 from the ts50x he currently has.

A little background, so please bear with me.

Found a ts125 that had not been used for about 15 years, the seller had replaced the top end and seem to have done a good job, took it for a test ride for about 4 miles and it seemed to go ok although there was a rattle from the clutch basket, the rattle disappeared when the clutch lever was pulled in. So thought it would be something simple and used it to knock 50 off the price, it was the only thing I could find as although its 20 years old its only done 8k and its not been messed with and is completely standard, paints a bit tatty but mechanically seemed perfect.

Got about 10 miles home and it died, like total loss of fuel or ignition on the M180! Anyway rang the seller and he came with his trailer and my money and offered to fully refund me which I thought was good of him but I said if he knocks me 100 off and trailered it home I'd still take it. He agreed.

Found tank full of rust, emptied, shook all the rubbish out, took out the fuel tap and clean and used the air line to blow through, cleaned the carb out, fiited an new inline fuel filter, pilot jet was totally blocked so thought I'd found the problem, but no, still the same. Kicking it over or running it down the road I don't get hardly any fuel into the bore, or a very small amount. The very occasional pop out of the exhaust. Thought it could be a problem with the reed valve assy so took the carb off again and the oil pump assy to get to a hard to get at bolt which then let me get the reed block out, although the curled plates were very rusty the reeds themselves were in very good nick, cleaned them back up and stuck them back in, exactly the same.

So now I'm thinking that the vibration was possibly knackered crank bearings which has caused the crank seal to fail and don't have an air tight crankcase which isn't now creating a vacuum to suck the fuel into the chamber.

Does this sound reasonable? I have now removed the engine from the bike and the plan is to take it to my friendly dealer to see if they can test the crankcase. Does anyone know if they can usually do this?

I'm guessing that it shouldn't take them more than an hour or two to do the seals if they are shot as I've taken the motor out, Can't do it myself as a couple of special tools are required, one being a stator remover.

Bit annoying really as it seems a pretty straight forward job.

So if there is any ts125 experts out there does my diagnosis seem correct ? Any help would be truly appreciated as I've got about 100 to get it fixed or try and buy a replacement engine for the same amount of money.

Cheers

Rich





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v8kid

posted on 5/4/10 at 06:58 PM Reply With Quote
I had similar problems with my yam250rd many years ago and your diagnosis sounds spot on. New bearings and the associated seals cured my case and I bought the stator extractor for a 5 if I remember correctly and must have loaned it out hundreds of times....blessed if I can remember who it was never returned it now!
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Wadders

posted on 5/4/10 at 07:06 PM Reply With Quote
Doubt its anything to do with the crank seals.
From your description of the events, it sounds like the carb still has crap in it. I would strip it completely and soak the body in gunwash or petrol overnight.
rebuild and check float height, also make sure the filler cap breather is clear.

Have you checked the airfilter? could be blocked solid.

Check the compression with your finger over the plughole, just to make sure the rings/piston are ok.

Al.






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RichardK

posted on 5/4/10 at 07:10 PM Reply With Quote
Did a compression test on the top end 75 psi, not sure if this is correct or not but is one of the questions to ask my friendly dealer as I can't find it anywhere in the manual, however this won't check the crankcase which is where I think my problem is.

Have checked and cleaned the carb twice, they are so simple and I've done plenty over the years and am sure its ok.

Cheers

Rich

Cheers

Rich





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handyandy

posted on 5/4/10 at 07:10 PM Reply With Quote
Hi Richard.....

Did you try running it without the oil pump connected ? ( use a premix of oil in the fuel tank ). Are / were you getting any fuel into the cylinder? how was the plug looking after several attempts at starting?

Tho it does sound like you are on the right path with the crankcase seals, sounds like they,ve gone hard from so little use etc .

I,ve rebuilt a few 2 stroke engines ( mainly X7 engines ), shout if i can help in any way.

cheers
andy

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RichardK

posted on 5/4/10 at 07:17 PM Reply With Quote
Andy, Plug is bone dry mate. Have been trying with premix as I needed it running so I could bleed the oil pump properly, but haven't got it running yet but has had the oil pipe connected up.

Cheers mate

R





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handyandy

posted on 5/4/10 at 07:25 PM Reply With Quote
Ahh, if the plug is bone dry then like "Wadders" has said , i don,t think its the crankcase seals, even if they were causing a prob you would still get some fuel mixture onto the plug.

Sounds like the carb is gummed up, even after the few miles you rode it, may have dislodged some dirt & blocking it somewhere.

might sound like a silly question....but are the fuel lines brittle and hard ( age & lack of use ) blocked etc.

cheers
andy

[Edited on 5/4/10 by handyandy]

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RichardK

posted on 5/4/10 at 07:32 PM Reply With Quote
If I take off the the carb and put my finger into the reed assy there is a small amount of petrol in there, I think the seal has completely gone hence the lack of vacuum.

Could be miles off, do you think a regular dealer could test the crankcase seals.

Andy, don't suppose you got a stator puller have you, all the other tools I could make I recon.

Cheers

Rich





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Wadders

posted on 5/4/10 at 07:36 PM Reply With Quote
Sometimes normal cleaning just isn't enough, even compressed air won't shift some blockages. Worth trying the overnight soak in solvent before you start ripping the motor down.

Give it a sniff of easy start down the carb and see if it runs.

Al





Originally posted by RichardK
Did a compression test on the top end 75 psi, not sure if this is correct or not but is one of the questions to ask my friendly dealer as I can't find it anywhere in the manual, however this won't check the crankcase which is where I think my problem is.

Have checked and cleaned the carb twice, they are so simple and I've done plenty over the years and am sure its ok.

Cheers

Rich

Cheers

Rich







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thunderace

posted on 5/4/10 at 08:22 PM Reply With Quote
75 psi is too low mate im sure its over 120 for that bike.anything unde 100 is bad on any 2t mate.
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Danozeman

posted on 5/4/10 at 08:26 PM Reply With Quote
Id go for fuel supply as has been said. It would still suck fuel in if the seals had gone and wet the plug. Is the tap bunged up?

The seals are a possiblity as its been standing but id be surprised if they just popped.


P/s the rattly clutch could be the operating screw, they wear the casing and rattle like hell.





Dan

Built the purple peril!! Let the modifications begin!!

http://www.eastangliankitcars.co.uk

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RichardK

posted on 5/4/10 at 08:27 PM Reply With Quote
Bone dry, probably wasn't the best description I could have used! No where near as wet as it should be would have been better, for example, say for every 10 kicks I'll get maybe 1 puff from the exhaust, so some fuel must be entering to be combustible.

As said before the reed valve is a little moist with fuel too. Unlike the little ts50x where most fuel goes straight into the bore a little extra can go through a separate route through a smal reed giving the little power band. This ts125 all fuel goes through the twin set of reeds so its got to have a fair amount of vacuum to draw the reeds back.

Cheers

Rich

Cheers

Rich





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RichardK

posted on 5/4/10 at 08:32 PM Reply With Quote
Thanks, that just the sort of info I needed. Cheers Rich

quote:
Originally posted by thunderace
75 psi is too low mate im sure its over 120 for that bike.anything unde 100 is bad on any 2t mate.






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ReMan

posted on 5/4/10 at 09:13 PM Reply With Quote
Fueling still
Rusty tank-itis,
Takes some shifting

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russbost

posted on 5/4/10 at 10:07 PM Reply With Quote
Why not put some petroil mix in a spray bottle & spray into the carb inlet whilst kicking over - if it then runs proves crank seals /compression etc is adequate for it to function.





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MikeRJ

posted on 5/4/10 at 10:15 PM Reply With Quote
quote:
Originally posted by Wadders
Sometimes normal cleaning just isn't enough,



I had a GSX250 a long time ago that was stood for a couple of years and despite stripping the carbs probably five or six times and, blowing through with an airline and soaking them in every solvent I could find including celly thinners I never got it running properly again until I got a s/h set of carbs for it.

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RichardK

posted on 5/4/10 at 10:18 PM Reply With Quote
quote:
Originally posted by RichardK
This ts125 all fuel goes through the twin set of reeds so its got to have a fair amount of vacuum to draw the reeds back.



Because of the above, if the reeds don't get sucked back the fuel will just sit it the reed block.

I think !!!

Cheers

Rich





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Canada EH!

posted on 5/4/10 at 11:47 PM Reply With Quote
Check for a product sold in Canada, that you put into the rusty tank and slosh around, this seals the gunk in and it doesn't flake off and get into the carb again, unfortunately I can't remember the name right now.
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skodaman

posted on 6/4/10 at 01:01 AM Reply With Quote
Probably not your problem but my old TS100 snapped the woodruff key for the rotor allowing it to turn. Took a while to find the problem as still had spark, compression and fuel. So worth a check if you can't find anything else wrong.





Skodaman

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Peteff

posted on 6/4/10 at 08:48 AM Reply With Quote
Nut loose on the crank so the timing is out and the generator is rattling and worn the woodruff out as Skodaman says. Have you had the casings off ? Try it as it's the simplest solution.





yours, Pete

I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.

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Danozeman

posted on 6/4/10 at 04:52 PM Reply With Quote
quote:

Nut loose on the crank so the timing is out and the generator is rattling and worn the woodruff out as Skodaman says. Have you had the casings off ? Try it as it's the simplest solution.



My ts50 did a similar thing. flywheel came loose making it hit the generator which then broke the mounting plate.





Dan

Built the purple peril!! Let the modifications begin!!

http://www.eastangliankitcars.co.uk

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Peteff

posted on 6/4/10 at 05:20 PM Reply With Quote
We saw it on a Yamaha RD350, it ran nicely then just cut out and wouldn't go again.





yours, Pete

I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.

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