Yamaha TRX850 Enthusiasts Forum

I've just picked up a pair of Mikuni TDM40 carbs stamped TDMR 40D6 T731.

The parts manual shows a linkage for accelerator pumps (part numbers 93/94) but there is no link and bellcrank on mine. What do others have on their TDMRs?

http://www.allensperformance.co.uk/images/exp-tdmr.gif

Think I'll answer my own question. The carbs were built from a bank of 4 for a ZZR1000. Only one of the carbs has the pumper and feeds the others by pipework.

Someone has a pair of carbs with a pumper and I've the other pair.

Has anyone used a set of TDMR40s without an accelerator pump? I'd be interested to know before \I send them back to Germany under Ebay misrepresentation rules

Cheers, Alan

I am using TDMRs with acc pump, yes. But I doubt if it will do worse without them.
All they do is just squirt a load of petrol in, getting the mixture too rich for a short moment.

Thanks Mr T. I was wondering if there would be a big flat spot under acceleration? I've dealt with auto engines where the accelerator pump has been faulty and the car has been a pig to drive through the "hole" in the fuelling.

The seller is willing to take them back - think I'll do it - unless anyone has used TDMRs without the pumper...........................................

Tried to set up a set of flatslides on a friends bike from a two stroke (no accelerator pump), don't do it.

Thanks MV. Out of interest, what 2 stroke had pumps?

I once had a racing RD200 with 32mm Amals which had powerjets fitted but they weren't mechanical pumps, they relied on vacuum to add the extra fuel at full throttle

Not sure, but these were jetted way too big stock, so I assume the two strokes are much richer but don't use a power jet, probably because they are usually at full throttle or off (or should be I guess!)

Even jetting them back to normal ish we still couldn't get consistent results with partial & quick WOT.

When my FCR41's had an accelerator pump fault (no fuel pumping) the motor ran dreadfully. The pump is there for a reason and it will be a pig to ride without it in my opinion.

Thanks for all your replies - I've sent the carbs back to Germany. Still looking around for a pair.................

So if you got hold.of a.full bank of four carbs it would be possible to make a set of carbs for a trx with a 40mms bores?

Try a zzr forum. That motor.has an issue with spinning main bearings so there will.be a.few sets of carbc with out motors around.

Yep, been looking down that route ☺