Hi guys.

I have been working through the manual today trying to diagnose why my long-term project isn't pulling well in the top end. It is an 88 2J but it’s running a PGM 2 unit, loom and ignition pickups from an 89 R5K, however it still runs the TA20 carbs (single solenoid) and piping as opposed to the 89 TA21 Carbs which run 2 solenoids.

I am apparently getting the correct voltage at the PGM2 for the solenoid that is still there, but obviously nothing for the second solenoid.

Does anyone know if the PGM will be unhappy not receiving a signal from both solenoids? Could this be my issue? Has anyone successfully run TA20s on a PGM2 or am I onto something?

Thanks all!

For a bit of context, the bike gets to about 8k and feels like it is breaking down under load. Other things i have checked prior to this are:

- Passed leak down test (Bottom end has been rebuilt ~100kms ago)
- RC valves seem to work fine, but are locked open for the sake of troubleshooting
- New reed petals fitted
- Had the carbies apart many times cleaning/looking for issues.
- Set, checked and re-checked float heights
- Jetting is standard with #150 mains (wire splice, airbox mod and tyga pipes)
- Tried multiple sets of plugs with newish caps
- Tested the coils and getting the same resistance on both.
- Checked the voltage out of the TPS which is in-spec according to the manual.
- Checked continuity between coils and PGM.

I am running out of ideas (and patience) so any suggestions would be appreciated.

To be fair, that's going to be almost impossible to diagnose without actually being there! Any correct guess will be exactly that, a lucky guess, given the mods and "bitsa" nature of the build I'm afraid. Wrong carbs, wrong air correction setup, with a modified airbox and race pipes thrown in for good measure... ouch!

To me, it sounds like an air correction issue. I've run both an R2J and R5K with the RC Valves pinned open and both ran well, but they both had the correct PGM and carbs for their respective model.

The PGM on every model is "linked" to the carbs, and I suspect the PGM-II with TA20s and a single solenoid just isn't happy. The PGM-II is more sophisticated than many realise, with different maps for each cylinder, TPS input (that not only measures position, but also speed of throttle transition) that alters timing, air correction, and RC Valve operation, as well as being RPM based. The TA20 and TA21 carbs differ internally, despite looking virtually identical from the outside, adding to the confusion.

It may well sound like a cop-out, but fitting TA21A carbs and the correct solenoid setup would be my advice. Without that, you're most likely just going to run around in circles. I'm sure you could make the setup work, but without prior experience, I expect it's going to be a bit of a ball ache! Sorry I can't be a bit more positive, but that would just be me leading you up the garden path, as we say over here!

Edit: Be aware the R2J and R5K static timing [flywheel] is also different, which too will effect the PGM-II operation.
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

Check us out on Facebook! Please "like" our page!

YIkes! sorry to hijack the thread but I started with an MC18 R4J but have had to replace everything, including an MC28 engine, new set of carbs (not sure which model) and PGM II (at least i still have the PGM i). This bike will be for track and race use only so is it possible to bypass all the above issues and simplify the whole system by eliminating the solenoids and other electronic gizmos altogether? I know of a local tuner who just pins the power valves open, and eliminates all related electronics. Not sure i want to do that.

Failing that, which carbs should i run and how are they identified?

Thanks.