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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> Valve timing one tooth out
Post Info TOPIC: Valve timing one tooth out
TTRfan


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Valve timing one tooth out
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Timing out.jpg

The photo is from a TTR250 engine I am just stripping down to check. The engine is at TDC and the cam sprocket lines should be parallel with the head.

This is the second engine in a week where a stutter and slight misfire has been caused by incorrect valve timing. The other case was a customer who had spent some time checking and adjusting his carb but, after my suggestion, checked and found his timing was also a tooth out.

I have had the same problem crop up a while back which is why I suggest in some of my posts that a simple check of the timing is made before taking out the carb.

So, remember, its not always the carb that may be causing issues wink

Brian



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andy m


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How does the bike run and what symptoms does it show when it has occurred ??

 



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TTRfan


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Starts and runs OK at low revs but "fluffs" and doesn't have power at mid and top range.

The other owner said "It purrs nicely at idle. But coughs and splutters like its not getting enough gas on any more than ¼ throttle."

Brian



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andy m


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Exact symptoms we have on a bike mentioned in another thread, checked carb, swapped my cdi and coil. Checked the meter reading on stator. Tomorrow we were going to change stators in case it was something under load. 

 

In your picture it looks like it has jumped on both cam sprockets.



-- Edited by andy m on Saturday 24th of May 2014 08:47:14 PM

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TT-R250M


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andy m wrote:

 

 

In your picture it looks like it has jumped on both cam sprockets.



 I see what you mean, it does look like that.

The cam chain is obviously stretched also and why they are not lined up properly.

However, I have a feeling that it did not jump at all and the person that did the timing used the ''H'' mark (ignition timing mark) instead of the ''I'' mark.

Jarrah

 



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TTRfan


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You are probably right Jarrah. Hadn't thought of that.

The engine has only done about 5k miles and the rest of the engine is looking good.

It might be the solution Andy - worth checking!

Brian



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TT-R250M


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TTRfan wrote:

You are probably right Jarrah. Hadn't thought of that.

The engine has only done about 5k miles and the rest of the engine is looking good.

It might be the solution Andy - worth checking!

Brian

 If it has been run like that for some time it would have stretched the cam chain from the engine running rough (and backfiring/misfiring). It does not look to be too bad from the picture but hard to tell when they are not lined up with the cylinder head.

Jarrah



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TTRfan


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It's actually pretty good. The photo doesn't flatter it wink



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TT-R250M


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TTRfan wrote:

It's actually pretty good. The photo doesn't flatter it wink

 Fair enough, I thought it looked not too bad from the picture but hard to tell (as mentioned) . smile

Jarrah



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matador


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For me, when setting say timing I set up & clamp off then give the engine a few turns and check again. bit like the old carpenters saying, 'measure twice - cut once'.

I have an approach to engines, where if I can't sort it out by checking the carb/ign - then it's something inside the engine. I had it with my TTR where I couldn't sort it out & it turned out to be the valve chain sprockets were set backwards - inlet set on the E line & exhaust set on the E line, from new.

Also with a 56 350 Matchless that wouldn't pull up hills = a load of internal faults now sorted, not that it runs like a TTR but same principle.

Have a good day bit wet here - last weekend = brill, on the Wessex Wanderer, 60 bikes across Salisbury plain area. 



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