Wessie34 Posted August 10, 2015 Share Posted August 10, 2015 (edited) Well here we go again you say ! I hope there's a fix for this cos it's doing my head in !ive done some trawling of posts on here and discovered a problem I didn't know I had, mines a 1980 model,2k4 engine, air filter on the right as you sit, and I believe it should have the 2H500 carb on it, mine has the 3U500 on (160 main ) but, I believe because the air filter I have is more restrictive it'll run rich! It didn't have a filter fitted so I assumed it needed one ( I'm guessing it was run without!)ps. Not used it yet. So, I don't want to source the correct carb cos ( I hope ) this one will maybe go quicker as the other is only a 130 main ! What do you say ? I know now that pod filters are out So can I fit a less restrictive filter of some sort? I have a K&N in at the 'mo but I'm guessing that is a direct replacement for standard, can you help please, Dave Edited August 10, 2015 by Wessie34 Link to comment Share on other sites More sharing options...
Moderator Cynic Posted August 10, 2015 Moderator Share Posted August 10, 2015 You have a 78/79 on a 1980 plate. Your frame number will be between 2K4-000101 the 2k4, 2k4-010101 the 2j2 or 2k4-020101, the 4j4.The later 1980 4j4 has the air filter on the left and the oil tank/battery on the rhs. You should probably have a 7 wire cdi too.With an air filter in it with the 160 it wont run, I would guess its someone doing some bad garage tuning. See if you can spot the id code on the jet needle. If its 4j13 you only need swap out the main jet for the correct one. Even so the bodies are pretty much the same, change the jet needle and the main and your 99% there. Easy fixed. Link to comment Share on other sites More sharing options...
Wessie34 Posted August 10, 2015 Author Share Posted August 10, 2015 Thanks Cynic, you do know your stuff. I'll check the jet needle tomorrow night. Am I right in assuming the engine will be ultimately less powerful as it's pulling less fuel and air ? ps. Mine's the earlier one. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted August 10, 2015 Moderator Share Posted August 10, 2015 Nope, the actual power changes buy very little.How it makes its power changes, the later bike is peaky, has less lower power and has to be kept on the pipe more with hills and such. Its also worse on fuel.Yours will have much better low to mid rpm manners but run off the pipe towards the redline.Think, MX and trials. Although in truth the differences are not all that remarkable. Certainly not worth swapping the airbox assembly. You will make up for any loss with a good exhaust.The best blend is actually the older cdi/mag on the newer bike.And the golden rule of DTs DO NOT RIDE THEM AT THE REDLINE, on modern fuel THEY WILL hole a piston. Blast it to the redline for an overtake or a bit of red mist but not sustained. Link to comment Share on other sites More sharing options...
Wessie34 Posted August 11, 2015 Author Share Posted August 11, 2015 I was thinking maybe search for a later air box ! A less peaky engine is what I want anyway, I can now use the filter I've just bought, phew. I'll check the jet needle and source the smaller jet, thanks for taking the time to explain it all, brilliant. Link to comment Share on other sites More sharing options...
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