07 Honda CRF 150 R - missing in mid range

rachel46, Mar 1, 6:09am
Swapped all parts over from another 150r to try and find the problem but no luck, the only thing I haven't tried is replacing the wiring loom, any of you clever peeps have any suggestions! Ta :)

therafter1, Mar 1, 6:19am
Before I went anywhere near any wiring I would remove and clean the carby. I have a suspicion that they have the emulsion tube type carby and if any crud gets into the carby, or if the bike is left sitting for long periods the crud blocks the little holes in the sides of the emulsion tube where the main throttle needle runs up and down. If any of these tiny holes are blocked it will cause problems in various parts of the rev range, either above or below the problem rpm range.

Do you find that it is fine off the bottom, then you have a dead spot/range of misfire, then it goes thru it and revs fine again ! . if so, you can bet it is the emulsion tube.

Once sorted, fit a good quality inline fuel filter, and when the bike is stored or not used for a period of time, use fuel stabiliser.

rachel46, Mar 1, 6:31am
Hi, i've got a brand new 150r that i've swapped the complete carby, coil, the computers, the whole side off the motor, tried 3 new spark plugs, removed the hour clock, to try and find the problem but its still missing in mid range

therafter1, Mar 1, 6:39am
Certainly sounds like a mystery alright, especially the brand new aspect.

You are obviously proficient enough to have done what you have done thus far, but your problem still sounds potentially like it is emulsion tube related.

Where are you sourcing the fuel from !

Does the bike have a good inline fuel filter !

It is worth pulling the carb again and taking the float bowl off and checking for particles (however fine) and removing and checking the emulsion tube.

rachel46, Mar 1, 6:49am
I had the Honda shop do this already, and my brother is a motorbike mechanic has also tried it, plus the brand new carb I tried made no difference - still ran like a piece of $h!t -tried fuel from a variety of garages, has a standard fuel filter. Since i've tried just about everything else I wondered if it is the wiring loom!

pollymay, Mar 1, 6:57am
Could be interference in the loom or perhaps some kind of pickup issue. Do they use a VR sensor to pickup a toothed wheel for an electronic spark kinda deal! If so look up the manual and check the clearance for the pickup as this can be an issue

therafter1, Mar 1, 7:18am
Yep, I'm out of ideas and you have it pretty well covered. It sounds like you are in specialist country. In saying that any good auto sparky should be able to go over it for you.

rachel46, Mar 1, 7:38am
thanks for your suggestions therafter1, there are a lot of clued up people that hang out in the motoring threads :-))

rachel46, Mar 1, 7:42am
thanks, gunna take it to the auto elect. hopefully will have some success there, if not will just have to keep it for parts (blardy expensive parts bike!) I brought it 2nd hand off TM and its never run right, probably why the guy sold it!

fro560, Apr 17, 2:00am
How did you fix it? mine is exactly the same??