Not reving clean at all

[kdx_cobra]

Good evening

My first post was about getting my exhaust in order. I now repacked the exhaust, cleaned the pipe, new o-rings and gasket + high temp silicone.

Previously I've rebuilt the carb with a moose kit, just put what they gave me in there without considering the jetting, assuming it would be standard. I have read that ppl say its too rich standard.

As far as I know my engine is completely stock except for FMF fatty pipe and exhaust + boysen reeds. Jetting should be normal (yes i was dumb enough not to verify when I installed it). The needle I believe I changed it from middle to one up, to feed more fuel. Carb cleaned, new hoses.

My tank is cleaned and new fuel valve, new hose to carb. Bike is always very easy to start.

Splutters, lots of smoke. I've been running on 3% oil, right now testing 2,5%.

Tested 2 new sparks - doing 0.75. Have not been driving it really since winter so can't tell you have the plug looks like at this time, but as I recall from last season it tend to be on the rich side, bit oily/gas, not really dry

Does not rev clean, doesn't sound as aggressive as it should. Splutters

I just tested compression, only cold though, and it was 165 which is very high I understand. Hopefully it's a good sign.

Airfilter clean and oiled.

What do the experts say, what is my next steps in correct order?

- Thinking re-jetting
- I also have a brand new chinese knock off carb 35 mm just for testing purpose
- Could KIPS be involved?
- Reed valve?
- Could there still be some leak somewhere even though compression is good?

Can't wait for the baby to rev as she should. Cheers

[Slick_Nick]

Test the ignition coil. That was my problem.

[kdx_cobra]

Ah, thats a good advice. I wasn't initially thinking this would be electrical.

[bufftester]

Jetting...
Stock jetting on its own is on the rich side. Then you add an aftermarket exhaust. Then you diddle with the needle. Pick a gas/oil ratio, then jet the bike to it.

[SS109]

I would first pull the carb and check your jetting, including what needle you have, and check to see if the jet block gasket is good. Here's how to check the jet block gasket...



Also check all electrical connections. My bike also wouldn't rev out due to a bad spark plug wire once. It was a real pain tracking that one down. Also had the internal pipe in the silencer break and caused a similar issue.

Anyway, point being is there are a lot of things that could be causing the problem so let's start with the easy stuff and go from there. Once you've done that with the carb and electrical come back with what you got and we'll help you sort through it.

[kdx_cobra]

Thanks for replies, it does make sense.

Silencer and pipe is good, so I will start by looking at the electronics starting with a new coil

Carb should probably be standard and run it a 30:1 as a starting point. Then work myself forward from that

[SS109]

Thanks for replies, it does make sense.

Silencer and pipe is good, so I will start by looking at the electronics starting with a new coil

Carb should probably be standard and run it a 30:1 as a starting point. Then work myself forward from that

Please, don't assume the jetting is standard. The bike is way too old to make that assumption unless you've owned it since new. More than likely, jetting IS the issue. Plus, just buying new parts is not the way to figure out the problem. Do the free and simple stuff first.

[John_S]

Did the carb rebuild kit come with jets and a needle that you used? A ProX 42 pilot jet caused me at least a couple hours of headache trying to get the bike to run right. The air screw setting was so far off and it would hardly even idle it was so rich. I cleaned the float seat, checked the jet block gasket, reset the floats and couldn't figure it out. I finally bought a genuine Keihin 42 pilot jet and it cleaned up immediately. I would throw the Moose needle and jets right in the trash and only trust genuine Keihin.

[doakley]

If it cranks fairly easily and runs, I would think more about jetting. I'm unclear about what you did to the needle setting. Did you move the clip one space up or did you raise the needle one space up?
One final note, my 220 absolutely will NOT rev properly unless the bike is really warmed up. I've put 3 different carbs on it and it was the same with all three. By warm I mean beyond idle warm up. I typically have to ride mine a bit, maybe a few laps around the parking area, to get it sufficiently warm to run correctly. Then and only then, it is spot on, smooth and **** hot! I cannot make any accurate adjustments until then.

[kdx_cobra]

Hi

Thanks for replies.

The rebuild kit came with jets, gaskets and needle.

I just got delivery of a bunch of jets, so I’m ready to take the carb apart again.

The jets I got are not original, but I do take note of what you say @John_S and @SS109. I will give it a try and if no luck order in the real deal from Keihin

@doakley I will have to see when I take it apart again, I forgot if it was up or down. So far mine has acted somewhat similar either warm or cold, but I hear you, how it revs when warm is what’s important.

I shall return when I tried some of your tips!

[Slick_Nick]

Test your ignition coil. Only takes a few minutes, and it will save you chasing a jetting problem over and over if it’s actually an ignition one.

[SS109]

Test your ignition coil. Only takes a few minutes, and it will save you chasing a jetting problem over and over if it’s actually an ignition one.

Yep, another one of those "free" things to check before spending money.

[KDXGarage]

Which KDX is it??

[kdx_cobra]

Hello all. I have not been working fast... but now I have an update and I'm eager to hear what knowledge you might be able to bring forward after this. Quick re-cap

This is a 1995 KDX200. Boysen reeds and a full FMF system that has been cleaned and new gaskets. Carb has new gaskets. During my tests now i have made sure its warm and also obviously included real driving with it.

1. I installed a new coil/cable - no difference
2. Removed jets that was in (160/48), installed 155/42 but not Keihin brand. Needle is no 2, that is, 2nd from top. At this stage I'm not sure how to determine if needle itself is original or not. - Positiv difference, dry-rev much cleaner. When driving it’s clearly better, but still lots sputter. I feel I gained bottom power, lost top power, rev cleaner low rpm than high. I forgot to pull plug and check it after this.
3. Set needle to middle (no 3 from top) - Felt this was negative, more sputter. I pulled spark plug, it was pretty wet.

My amateur analyses tells me that I should keep needle at no 2 from top. Then again try different setting Jet's - but which, do I go up on Main?

Cheers
Matt

[kdx_cobra]

And I might add that I have compression tested it with very good result.

Extremely easy to start, almost always of first kick.

[SS109]

Sounds like it's still rich to me. Moving your needle from clip 2 to clip 3 and it ran worse tells you it's rich. I would try one step smaller on the main. Also, you mentioned before, you went to less oil in your premix. That actually makes the bike richer as less oil = more gas. What is your elevation?

[kdx_cobra]

Thanks. Yes it's obviously running rich. I know each bike unique, but when i check this

https://www.revzilla.com/assets/0000/95 ... 891994.pdf

Even they recommend a somewhat very rich setting. I understand this is science...

Last time riding I can imagine I'm at 400-600 m elevation.

One step smaller you say, I will try that. Damn, i believe the 155 was the smallest in the kit that I got....

[bufftester]

You absolutley need to do the jetting from the beginning instead of just jumping around trying stuff. Get your Air Screw and Idle Jet sorted before doing anything. That is the baseline for all the remaining work. Change one thing at a time and then test. Yes it takes time and is slow, but it is the only way to do it right.

[SS109]

You absolutley need to do the jetting from the beginning instead of just jumping around trying stuff. Get your Air Screw and Idle Jet sorted before doing anything. That is the baseline for all the remaining work. Change one thing at a time and then test. Yes it takes time and is slow, but it is the only way to do it right.

100% agree! Also, try to stick with genuine Keihin jets. Aftermarket versions normally don't mean squat when compared with Keihin's numbers or at least stick with the same brand through the process.

[kdx_cobra]

Thanks, I sure have some work to do. Will return with updates once tested