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Top End Wont Rev Out ?


spokes
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D36 Needle

105 Main Jet

36 Pilot jet

268K Nozzle?

Spokes, have you check to make sure the fuel petcock is clear?

Next time it does it, try pulling on the choke. Does it help or make things worse?

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I have done everything at least three times now !

Apart from a new piston and cylinder which are OK !

Petcock was full of s@*t so thats clean now no diffnce.

The float levels are bang on but there is some wear on the levers where the floats push on them.

The exhaust was last stripped down, cleaned, repacked and sealed about 10 hours riding time ago. There is a fair bit of carbon build up, more than I expected ?

When the bike splutters it does chuck out a fair bit of smoke !?

I am still thinking fueling but more towards Ignition Advance faults now !

One bloke seemed to think that there maybe a possibilty that the crank seal behind the flywheel may have worn thus letting un metered air into the crankcase ?

I'm gonna go thru everthing ( one at a time ) again tonight !

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An easy way to determine if it's a left side crank seal is to pull on the choke. This will deliver more fuel that should help offset the lean condition created by a leaking seal.

The other possibility is that it's a right side crank seal, letting transmission oil into the crankcase and making for a rich condition. If this is the case the choke will make it much worse.

Always wise to check electrical connections and grounds. I am doubtful about the reeds causing the problem, but can't hurt to look. Normally damaged reeds effect the lower end and midrange more than top end.

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Not the reeds cos I have replaced them whilst trying to eliminate this problem.

I will take the tool box with me to Buxton on Sat ( Gas Gas open/Test ride day ! ) Will try and badger some of the GG Mechanics there !

Will check all of the connections again ! Being an Electricain, I am well aware of the effects of vibration and heat on electrical connections !

JTT, I will do the choke trick when I get the bike back together !

I think that my problem maybe that I took too many things apart when I first got the bike ! Thus I may have caused the problem myself !! :ph34r:

I will get there in the end ! ( When I buy a different make of bike ! )

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It seemed to run OK all day yesterday but there are no real open throttle climbs at Hawks Nest.

It is loads more grunty since I did the rings and it got me over everything yesterday without a problem.

It did play up a bit when I ran it at speed up and down the road. ( Bunt my leg on the exhaust after this, ouch ! )

I got a funny smell after I last repacked the rear box and I sometimes get a the same plastic kind of smell when the bike is hot after a bit of a blast.

I am using ATF DEX III ( Valvoline ) and its due for a change today.

I'll get it nice and hot then I will measure the amount that comes out.

If its the crank seals is it just a matter of pulling the clutch assy. out and tapping a new one in place ? Same with the flywheel side ?

Gotta sort the clutch out as its dragging a bit so I can do it all at the same time !

New rear tyre, clutch and cank seals next week new rings last week ! Will it ever end !? Probablynot ! :ph34r:

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If its the crank seals is it just a matter of pulling the clutch assy. out and tapping a new one in place ? Same with the flywheel side ?

If your crank seals are leaking its highly likely that the main bearings are worn - the leak is usually due to movement in the main bearings, just replacing the seals will only mask the problem for a short length of time.

The only real solution is to strip the motor & replace the main bearings & crank seals together. Its not going to be a big job but will save you having to go through the same rigmarole in 3months time.

This is a common problem in MX bikes where the revs are a lot higher for longer periods & replacing seals & main bearings is seen a regular maintenance.

Buy yourself a fourstroke and you wont have this to contend with anymore!

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I'm gonna play with the needle height today. And New plug.

Got to do the GB oil first tho.

I had a good pull on the piston when I did the rings last week and could not find any play apart from piston side to side movement.

Could'nt practice on a 4 stroke round here. Too noisy.

We only just get away with 2strokes !

Edited by Spokes
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Right then,

I am pretty sure that I have a crank seal problem !

I cant find any movement in the mains but the smoke does smell wierd and the choke makes things a little worse.

I have looked at the 03 parts catalogue and I can see parts 18 and 21 on the crankcase diagram which are both seals

It looks to me as tho I can change the Flywheel side OK but the right side looks more tricky ?

Why are there 2 no 21's on the exploded diagram of the crankcase ?

Has anybody done just the seals before ? Has the engine got to be split ?

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Just ran the bike outside my house for a few minutes when all of a sudden it ran perfectly for a few seconds and then stalled.

The fuel tap was off and it ran out of fuel !

This must meen that the float height is wrong ?

I have set te float height correctly so many times !

It must be wrong as it is now ?

Gonna lower the float heights in the morning.

Looks like it maybe a simple problem after all !

Fingers crossed !

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It ran better with the floats a little bit lower ( i.e. the levers just above level when upside down )

Went Here and ran the bike with no problems all day apart from VERY top end of the rev range.

That is until the clutch cover gasket started leaking !

Checked for play in the mains and none what so ever so forgeting about the crank seals for a while.

Does anyone have any test values for the Ignition System ? i.e. coil resistances and readings accross the Ingition module wires etc.

Cheers

R2, Will check thoses ring sizes for you soon ! Not forgot !

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