23 replies to this topic

[honda_tlr]

Right, My TLR 200 is running like a dog , but only at high revs , if you ride off ,1st 2nd 3rd 4th 5th ect full throttle it runs fine till it tops out in 5th, but if its left in any gear , lets say in 1st and you open the throttle right up , once it "tops out" in that gear it will then run with a miss fire , it will run like that but sounds really nasty , Now then , speaking to a bike mechanic at a trial the other day he said it sounds like its over fueling and that its something to do with the carb , Ie time for a new one or smaller main jet ?
If you blip the throttle and let it off again it will rev up and back down really nicely , but if you open the throttle and hold it open thats when it runs really bad , so basicaly at high revs.
So , does this make sense to any one ? if so whats the cure to my problems.

It has done this since I bought the bike and its starting to get on my nerves.

I have cleaned the carb loads of times and also put various new plugs in but non of them have sorted it.

I plan to polish in side the carb with a buffing wheel and some Autosol to make sure its all really clean.

The bike also carbon fouls the plugs up. The clip on the needle was set in the middle position ( 5 positions in total) so I put it on the highest one and now the plugs are still black but not as bad , there is now white smoke coming form the exhaust, i haven't played about with the mixture screw on this different clip setting so is that what I need to try now ? ( it is not the piston rings causing this as they were changed a few months back)

Or won't I be able to get a nice plug colour with the bike running the way it is ?

Cheers.

Edited by honda_tlr, 30 October 2007 - 12:55 PM.

[max1956bikes]

messing about with different jets only masks the problem make sure they are correct size to start with i cannot remember the sizes hopefully someone will come and say soon.needle clip should be 1 down from top leave it there.dont buff throtle slide it will change the size.i would check tappets and change plug cap and make sure wires are nice clean contacts, good earth to coil and coil tighten to frame,disconnect cut out switch.if still no good try running without hose to carb,not for too long dont want any dust getting in. try these things first .richard.

[paul w]

there are so may little things that it could be, but changing needle positions and main jet sizes is the wong way to go. as previously posted this is "masking" the problem.
are the valve clearances ok?
air filter clean?
when the rings were replaced did you do a valve leak test?
are there any air leaks on the carb side?
does the white smoke smell of burnt oil?
there is almost certainaly a problem with the bike. it may be prudent to have it looked at by a shop, before it costs a lot of money to repair.
let us know how you get on.
paul.

[honda_tlr]

"are the valve clearances ok?" Yes
"air filter clean?" Yes
"when the rings were replaced did you do a valve leak test?" Yes
"are there any air leaks on the carb side?" No
"does the white smoke smell of burnt oil?" No

"there is almost certainaly a problem with the bike. it may be prudent to have it looked at by a shop, before it costs a lot of money to repair."

I'm not taking it to a shop, I am very capable of working on bikes , just restored a 1956 Ariel colt.
Cheers

Edited by honda_tlr, 30 October 2007 - 11:20 PM.

[paul w]

i didnt mean for them to fix the problem, just correctly identify the problem. its only from experience that i advised that. i worked for several years as a bike mechanic and saw lots of cases like this ,after the fact,far too late.

[honda_tlr]

paul w, on Oct 30 2007, 06:31 PM, said:

i didnt mean for them to fix the problem, just correctly identify the problem. its only from experience that i advised that. i worked for several years as a bike mechanic and saw lots of cases like this ,after the fact,far too late.

The guy I spoke to on Sunday owns and runs Betws moto in Betws y Coed.
So he should know what he is on about

[Slapshot 3]

this is a good thread because I have a dog that's running like a Honda.......

honda_tlr, what to have a look at is your Valve timing, after I rebuilt mine a couple of years ago before i swapped it and what not, as i built the revs up it got quite noisy, rattley and rough as sin. Tried everything in terms of carburation, cleaning it again changing jets etc etc etc i the end on a tip from someone else I looked at the valve timing.

When I had attached the new timing chain to the cam sprocket it slipped about two teeth from the marking basically to do with rebolting the sprocket in place. In the end after I set it up allowing for the slippage it ran a treat, clean and smooth from the bottom and revved out nicely all the way up through the gears.

Have a look, no need for a big strip down just check the timing marks on the head.

Hope this helps

Edited by Slapshot 3, 30 October 2007 - 11:16 PM.

[honda_tlr]

Slapshot 3, on Oct 30 2007, 11:16 PM, said:

this is a good thread because I have a dog that's running like a Honda.......

honda_tlr, what to have a look at is your Valve timing, after I rebuilt mine a couple of years ago before i swapped it and what not, as i built the revs up it got quite noisy, rattley and rough as sin. Tried everything in terms of carburation, cleaning it again changing jets etc etc etc i the end on a tip from someone else I looked at the valve timing.

When I had attached the new timing chain to the cam sprocket it slipped about two teeth from the marking basically to do with rebolting the sprocket in place. In the end after I set it up allowing for the slippage it ran a treat, clean and smooth from the bottom and revved out nicely all the way up through the gears.

Have a look, no need for a big strip down just check the timing marks on the head.

Hope this helps

Ah right , I will investigate this a bit further then, also I have a timing strobe gun so am I correct in thinking that If I take out the small flat headed screwdriver nut on the flywheel side of the bike I can see if the timing marks are lining up at high and low revs .....?

[Slapshot 3]

honda_tlr, on Oct 30 2007, 11:26 PM, said:

Slapshot 3, on Oct 30 2007, 11:16 PM, said:

this is a good thread because I have a dog that's running like a Honda.......

honda_tlr, what to have a look at is your Valve timing, after I rebuilt mine a couple of years ago before i swapped it and what not, as i built the revs up it got quite noisy, rattley and rough as sin. Tried everything in terms of carburation, cleaning it again changing jets etc etc etc i the end on a tip from someone else I looked at the valve timing.

When I had attached the new timing chain to the cam sprocket it slipped about two teeth from the marking basically to do with rebolting the sprocket in place. In the end after I set it up allowing for the slippage it ran a treat, clean and smooth from the bottom and revved out nicely all the way up through the gears.

Have a look, no need for a big strip down just check the timing marks on the head.

Hope this helps

Ah right , I will investigate this a bit further then, also I have a timing strobe gun so am I correct in thinking that If I take out the small flat headed screwdriver nut on the flywheel side of the bike I can see if the timing marks are lining up at high and low revs .....?

In theory yeah though I never needed to go that far. Once I had the valve cam sprocket sorted it automaticall lined everything up. Use whatever method you can that was how I got round it. Could be other things as well but that rang a bell with me

[ScrumpyJack]

A friend of mine who specialises in TLR's has said this sounds like a poor CDI earth,, apparently its a very common problem and is easily fixed in about 5 mins,
I hope this helps

SeeleyJack

[honda_tlr]

ScrumpyJack, on Oct 31 2007, 08:51 AM, said:

A friend of mine who specialises in TLR's has said this sounds like a poor CDI earth,, apparently its a very common problem and is easily fixed in about 5 mins,
I hope this helps

SeeleyJack

Ah right , is this the one thats earthed by the air box ?

[Big John]

honda_tlr, on Oct 31 2007, 09:43 AM, said:

ScrumpyJack, on Oct 31 2007, 08:51 AM, said:

A friend of mine who specialises in TLR's has said this sounds like a poor CDI earth,, apparently its a very common problem and is easily fixed in about 5 mins,
I hope this helps

SeeleyJack

Ah right , is this the one thats earthed by the air box ?

Under seat by the air box, green wire usually I have been reliably informed!

Big John

[honda_tlr]

Big John, on Oct 31 2007, 05:51 PM, said:

Under seat by the air box, green wire usually I have been reliably informed!

Big John

In that case the CDI earth is clean and connected properly.

[g4321]

Does the spark look weak - if so disconnect and throw away the kill switch, check and clean all connections in the ignition circuit. , including spark plug cap. Fit a new plug - possibly even try a hotter plug.

have you checked float height?

If it is only happening at high revs then perhaps it is a weak valve spring allowing valve bounce?

The 'black' plugs may relate to poor mixture lower down the rev range where the bike spends most of its time.


The comments about timing relate to valve timing and not ignition timing, the ignition timing is fixed on a tlr with the flywheel and CDI pickup running off the crankshaft. Valve timing can be adjusted and is set by positioning the camshaft relative to the crankshaft - hence the comment about one or two teeth out.

If its only happened since you rebuilt motor then perhaps this is the case - although (I doubt if bike would rev well if valve timing is out.

[honda_tlr]

g4321, on Oct 31 2007, 10:12 PM, said:

Does the spark look weak - if so disconnect and throw away the kill switch, check and clean all connections in the ignition circuit. , including spark plug cap. Fit a new plug - possibly even try a hotter plug.

have you checked float height?

If it is only happening at high revs then perhaps it is a weak valve spring allowing valve bounce?

The 'black' plugs may relate to poor mixture lower down the rev range where the bike spends most of its time.


The comments about timing relate to valve timing and not ignition timing, the ignition timing is fixed on a tlr with the flywheel and CDI pickup running off the crankshaft. Valve timing can be adjusted and is set by positioning the camshaft relative to the crankshaft - hence the comment about one or two teeth out.

If its only happened since you rebuilt motor then perhaps this is the case - although (I doubt if bike would rev well if valve timing is out.

The bike ran like this before having new piston rings.
I think I'm going to take all the wiring apart and check for lose connections and bad earth's (anything else to look out for ?)
I will admit I haven't checked the float hight , how would this cause problems at only high, continuous revs though ?
Could something so simple as the mixture being out cause Problems like this ?
The spark is a nice, blue , bright colour.
Will a Cb750 spark plug cap do just to check that it's not that at fault ? (there the same plugs)
Cheers for all your help so far guys.