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Hot Starting Problem


dirtrider
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Has anybody had any trouble starting their TLR, Seeley etc when hot?

I did my first trial on the Seeley a couple of weeks ago and it ran fine for the first lap, stopping to inspect each section and then starting it again. However, at the end of the second lap, by which time the engine was well warmed up, I stalled it on a section(my fault) and could'nt restart it. After a long push back to the van, you can guess what happened, it started first time.

I got going again, but it was fading on sections at low revs, and it cut out again.

Retired first time out, not a great start! (Didn't mention the puncture I had to fix after the very first section).

I've since stripped and cleaned the carb, checked float level, flushed out the tank, replaced HT lead and cap, checked all connections etc.

It starts easily from cold but won't start when hot. Petrol is'nt getting into the cylinder since the plug is bone dry. I've had this problem on my Cheney BSA pre 65 motocross bike, which was fuel vapourisation. I cured it by fitting a tufnell spacer between the carb and cylinder head.

However, the Honda already has a spacer and heat shield.

Any suggestions?

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Couple of thoughts - all you have probably tried/done already.

Spark Plug - No doubt you have tried a different plug & are using correct plug - one other thing to try (I have seen this on another Honda) is try a non resistor plug. Its not like a two stroke where the plug always appears wet when it aint sparking.

Have you cleaned out the fuel filter on the bike - if its a 250 there is a separate filter, I have had problems where water (and dirt) has partially clogged the filter causing the bike to run badly when hot, missing and stopping as you describe. If its a 200 there will be a filter above the fuel tap within the tank. I found this on my bike a few times - probbably due to condensation - steel tank & wooden shed & cold weather = condensation = water in fuel = pain in neck!

In addition check that the vent hole on the tank is clear - again this can cause starvation.

The only other thing that comes to mind are valve clearances - if these are tight when the bike gets hot it will either not run or run badly.

If its an electrical fault, start by disconnecting the kill switch - just in case. Then if you have a mate with the same bike perhaps try swapping the coil & CDI one at a time, this to me is easiest way of identifying electrical problem.

I would check the valve clearances before you go any further.

Gordon

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Gordon

I'm chancing it in a trial tomorrow. It's really the only way to try it out properly. The main purpose is to try and sort it, although it would be nice to finish. I've put a couple of different grade plugs in my pocket to try.

I've cleaned all the filters as you described, but I think it will be a good idea to check the valve clearances again. 3 thou I think is what they should be. Better go and have a look and adjust them.

Thanks for the advice, I'll let you know what happens after the trial.

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Strangely enough I had a similar problem while out practicing today - after some detective work it appears to have been caused by a kinked petrol pipe restricting flow and causing a partial air lock. The pipe is between tap and carb - the TLR250 has a remote tap.

Gordon

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Unfortunately the problem persists. I'll check the petrol pipe for kinks, Gordon, and anything else that might cure it. It did start form hot OK sometimes today but sometimes I had to wait for it to cool down.

I think I'll just have to go through everything again and see if I can find anything. Either that or just stick to the B40 which starts first time hot or cold.

Who said pre 65 bikes were unreliable?

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Honda RS

How can you tell if the carb is badly worn? The throttle slide doesn't feel sloppy in the carb body at all. Also if the carb is worn then wouldn't it run badly when cold?

I assume that a badly worn carb would result in a weak and perhaps variable mixture by allowing air to pass when it shouldn't?

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  • 1 month later...

Hello lads,

Just got myself a lovely looking Seeley...a brief 1st plod around the garden really got me excited....attempting to ride up a fairly innocent bank proved to be disappointing as the enging 'bogged' a little. The carb on the bike is a Keihin PC 04C, needle appears a little worn so I've sent the whole carb off to Allen's Performance R & D to get it checked/refurbed.

Will keep you posted..

Oh yes, anyone have any idea how I can get the year of manufacture verified as I'd like to get an age related plate...thanks a lot, Mark.

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