Struggling to run over 110klm/hr

[Aussiesven]

Long time no post - g’day fellow Tenere riders:

Am about to embark on a week’s riding, so time to check the bike over and all is well, the 34L is ready to go, but...

It seems far too gutless above 100klm/hr. It seems to struggle, and even coughs / hesitates most times (but once only) when you rev up from say 90 or 100 onwards. Hard to get past 110 (yes, I am tall and heavy, but it used to get to 130-140 decades ago...

Coil is new, spark plug is brown (a tad too brown maybe?), carbie cleaned and fuel flow good. Had the carbie apart a few times, but nothing looks out of place. Jets are (I think) 125 in the secondary, but don’t 100% recall. Secondary butterfly is horizontal when fully open.

Suggestions? CDI? Needle setting too high? Compression (engine was overhauled a few thousand klm ago.

Bit stumped.

Sven

[Mezo]

Welcome back Sven, last seen in 2017

How did you break in your engine? hard or gently? did you hone the cylinder & were the ring gaps corect? Google motorcycle engine break in after rebuild for some reading, you can make a slow engine or a fast engine simply by the way you run it in after the rebuild.

Check the compression firstly.

Mezo.

[Aussiesven]

Mezo! Good to see you are still active! Yes, it has been a while...

Barrel has been honed, new rings, but old piston as the tolerances were still ok. Run in was slow, I don’t rev the crap out of the engine anyway.

Haven’t done a compression test, which may show low power, but wouldn’t explain the cough on acceleration!?

Sven

[Mezo]

Did you tank fill with water after it went under? im wondering if some rust has formed & gotten in to the carb, you did check the float needle valve filter when you pulled the carbie down?



Mezo.

[Aussiesven]

Valve and seat were all replaced. Every carbie part was cleaned and checked. Seals replaced.

I wonder whether I got the needle setting wrong or something like that. The cough must be carbie related... doesn’t make sense it is engine related as it’s not consistent. Double checked valve clearance and spark plug gap - all good.

As it feels like it’s running fat, maybe I should try removing the airfilter lid or elements (short time only of course, just to test the theory..!?

[Mezo]

Do you still have the other XT Sven? you could swap carbies to rule out that problem.

Mezo.

[motorang]

Hi,

1. Any oil temperature info?
   If the pickup fails there may be not enough spark advance, letting the engine run hot.
   You can try measuring the pickup coils:
   viewtopic.php?p=32779#p32779
2. It CAN be the CDI but that is rare. Only check I know of to make sense is to swap CDI to/from a bike that is running sweet ... Same goes for Ignition coil/wire/spark plug cap
3. Spark plug may have an issue, thats an easy check/replacement. Is it the standard NGK stuff or something special?
4. On my Tenere I had the spade connectors on the ignition coil coming loose when agitated by airflow only (overtaking).
5. Side stand switch if you have one.
6. What air filter do you run? There are aftermarket two-layer ones which do not allow enough airflow. Original or Twin-Air work fine.
7. Did you have a look at the air filter actually? If there is too much engine oil around or there is some blow-by, engine oil gets vented to the air box, clogging up the filter.
8. Fuel cap breather may be clogged and lead to fuel starvation. Can be opened and checked.
9. May as well be a faulty kill switch or ignition lock. You can detach the black-and white wire from the CDI which removes the kill "functionality" from the CDI.
10. A standard problem would be damaged intake rubber boots where the rubber detaches from the aluminium flange, maybe only at high load.
11. You can check if the secondary carb slider goes up smoothly. It is actuated by suction in the inlet at high load. You can try with carb on the work bench, bu putting a vacuum cleaner where usually the cylinder would be, and setting the secondary butterfly to horizontal position.
12. When checking the carb, did you use new hoses, especially to connect primary to secondary carb? All connections secured by clip or cable tie?
13. When checking the carb, did you clean the channel inside the primary float bowl that feeds the port to the secondary carb? At least on my 1987 model this runs inside the float bowl wall

Now I am running out of ideas :D

Andy