14 replies to this topic

[schmo9]

Need your help guys....background first... done the valve clearances, put them all to high end of spec.... 0.3 exhaust and 0.2 intake. While in there is noticed the intake cam was, give or take, 1 tooth back from lining up with exhaust mark (TDC) so lined that up while in there. All back together and sync'do carbs..but now I have a rich condition below 3k. Tried adjusting idle jets but I don't seem to be getting any effect whether 1 turn out or 3 turns out, both carbs and still rich and fouling plugs. Over 3k and performance is great. I've had carbs out, checked float height (14mm)...emulsion tubes renewed last year.. I'm stumped by this as it's only happened since doing valves and timing.
Is it related or coincidence..

I've had cam cover off twice to check my work and everything appears to be as it should. What have I missed. Why idle jets having no effect when adjusted??

Please come back and embarrass me with something simple I've missed..

Cheers

[Studley Ramrod]

Difficult to know for sure but here's a few suggestions.

 

Make sure the engine is warmed up and the tickover is as low as it'll go without stalling before you adjust the pilots and/or do a carb balance.

 

Check the condition of the choke plungers, if they're foobar'd they'll be letting fuel past them.

 

Check the position of the needle clip, it should be on the middle setting.

 

Check the vacuum pipes are plugged and there are no splits in the pipes.  Had a scottoiler on mine with a faulty connection which was letting air into the vacuum pipe, had rough running at low revs and non-responsive pilots until I fixed this.

 

Check for air leaks around the inlet rubbers.

 

Try adjusting the floats if none of the above works.

[schmo9]

Cheers mate....have walked away from it for the night..been at it all day. Will check for vac leaks tomoz.. what is the preferred float height, currently at 14mm?
Bike starts on the button no problems and runs in the garage great..blip the throttle and response is great, no drop before rise. Leave it running then take plugs out and they look great...the minute I take it for a test and 200 yds up the road if I'm less than 3k and open throttle, it starts to bog and hesitate but then ok after 3k...back to garage and plugs are pot black. Idle jets are 2 and 3/4 turns out... same settings as before..
It's undriveable under 3k..

[Studley Ramrod]

Sticking choke ?

[schmo9]

Well... I've tried pulling the choke on when it's idling (warm)(it idles great too) and it dies.. so I was thinking the choke is ok..

[Studley Ramrod]

Hmmmmm, sure is a bit of a head scratcher Schmo.  Keep us posted on yer findings.

[schmo9]

Will do... hopefully gain some wisdom in my sleep...be back out first thing tomoz...the pain in the ass bit is having to keep taking fuel tank on/off, battery in/out for each small adjustment, go a run then start again... gonna have to list all inputs again and check each one...again

[TYREDNGRUMPEE]

Here's one for you.

The IN and EX marks on the TDM camshaft aren't exactly exact in practice.. They never align perfectly with the head. Neither is the camchain run, tensioners etc.

If you've favoured one mark over the other and then used a best est. then you may end up having a perfectly mis-timed engine.

That camshaft you retimed?

Probably lined up perfectly to start with and now one tooth out.

[schmo9]

But would that cause a rich condition? I don't mind stripping all back off to reset to 1 tooth back on inlet..

[TYREDNGRUMPEE]

But would that cause a rich condition? I don't mind stripping all back off to reset to 1 tooth back on inlet..

 

I don't know.

I do know that I am 100% sure that things will improve when you re-examine your cam timing.

Make marks with tipp-ex, count rivets, keep the exhaust (front run) tight and return the settings to original, bearing in mind that either of those marks WILL NOT be perfectly in line with the head cover line.

You are in the best position to be able to recall what you have already done.

If there is wear, then the front exhaust run should be slightly retarded, perhaps giving the appearance that the inlet run is even further retarded.

Many base their measures on what they see with the upper chain guide removed, which further confuses matters.

[schmo9]

Ok.. I know exactly where it was to begin with and won't be a problem putting back...at the very least it will discount it as the issue... could do his with my eyes shut now..lol

[dapleb]

If ewe search on ear ewe will find pics of cam alignment (or not).

Did ewe replace mulshions with cheap replacements?

[schmo9]

Ok..problem solved! Tyredngrumpee's post was right but it's clearly easy to get confused with what's in the manual and reality...
This pic shows the timing at the start..





This pic shows my adjustment...




Needles to say the timing is now back as per the first picture and problem gone.

I've been trawling through forums everywhere to explain the condition I had and this exert explains it best..

"The point in the cycle where the intake valve opens is very important. If the intake valve opens too late in the cycle, the initial amount of fuel/air mixture draw into the combustion chamber is reduced and spent gasses will not be effectively flushed from the chamber. If the intake valve opens too early in the cycle, vacuum will be reduced and exhaust gasses will be forced into the intake manifold. When exhaust gasses are forced into the intake manifold, vacuum is adversely affected and the intake runners will soot up. This effect is called reversion."

Exert from here..

http://www.austincc....e/camtheory.htm

Hope this helps the less experienced of us..

Thanks for all your responses.

Edited by schmo9, 16 July 2016 - 11:06 am.

[Studley Ramrod]

The best way to check if the cams are lined up correctly is to look for the dot stamped onto the camshafts, just where the cog is bolted.  These should line up with another stamped mark/line on the camshaft holder.  Haynes manual page 2.13 pic 8.3c shows where they are.

 

Glad you got it sorted anyhoos.  Happy biking !

[Catteeclan]

Easy to forget the chain stretches.