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Rev 3 270 poor starting


tomtom385
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I don't know if this is any help but my Rev 3 was hard to start when warm when the main bearings/seals had gone. I needed to replace mine because they sounded rough, but a nice side effect was curing the poor starting completely. It's not a quick job but maybe if yours sound rough this could be contributing? 

 

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Mark,

Thanks for that, replaced the mains and seals 3 to 4 years ago and to be honest its most probably done less than a 100 hours in that time, I think that it might be worth changing the seals, my memory is failing me at the moment. Can the seals be replaced without splitting the crankcases?

TIA

tom,

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A lean mixture can make hot starting difficult.

Flywheel side seal leaking can cause this.  I think you can change the seal without splitting the cases.  Remove flywheel and pull out the seal with a small hook.  I have also seen a self-taping screw into the seal used to get a grip on it.  Just be careful not to damage the shaft.

New seal will tap in.

Other potential sources of lean mixture are leak in inlet manifold and blocked pilot jet.

Has it always started badly or was it OK once?

Once you have excluded all other issues you could try changes in the carb to richen the mixture to see if this helps.

PS does it hot start better if you use a bit of choke.  If yes then issue is in the mixture.

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20 hours ago, stu109 said:

A lean mixture can make hot starting difficult.

Flywheel side seal leaking can cause this.  I think you can change the seal without splitting the cases.  Remove flywheel and pull out the seal with a small hook.  I have also seen a self-taping screw into the seal used to get a grip on it.  Just be careful not to damage the shaft.

New seal will tap in.

Other potential sources of lean mixture are leak in inlet manifold and blocked pilot jet.

Has it always started badly or was it OK once?

Once you have excluded all other issues you could try changes in the carb to richen the mixture to see if this helps.

PS does it hot start better if you use a bit of choke.  If yes then issue is in the mixture.

Stu109,

I think you might have something there, used to start ok. I thought that it might be me as my kick ain’t what it used to be. Plug is quite black which might suggest it’s running rich. Will replace the seal, cheap easy fix. Will have the carb off as well, thanks for the advice

cheers

tom

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When starting you are mainly using the pilot circuit in the carb, so the colour of the plug, which is an indication of mixture in normal riding, is less relevant.

Check the carb to inlet manifold rubber for splits whist you have the carb off.

Have you adjusted the mixture screw at any time?  Adjusting this whist the engine is running may help.

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