Maxim X lean surges like crazy.

I have stock jetting and 1 washer under the clip in the needle. The air screws also are set to 3.5 or 4 dont recall. Carbs are well synched and this is a Maxim X so I dont have the equaliser manifold.

And between 1/4 and 1/2 throttle under load, running 4-6K rpm in 5th or 6th, the thing simply does not hold steady rpm at steady throttle.

Has any one else had this problem, and is it solvable with more washers under the needles ?

Has any one had to swap main jets or anything else on a max - X.

Stock filter and pipe on this BTW.
Many thanks.

Cool.
Srinath.

 

when it surges, have you tried a plug chop? that will give you an idea which cylinder is causing the issue.
can you get it to reproduce in 1st or second gear?

 

I have not done plug chop test. However I suspect that its all 4. Cant see this being limited to 1-2 cyls. Good next step if I dont get it figured out though.
And I dont run too much steady throttle in 2-3 - well I could, but I am not seeing the relevance though,
Cool.
Srinath.

 

4 to 6 k is right in the midrange right? I would check the emulsion tubes* if they are ovally worn. And the needles themselves if they still have a nice taper to them.
(* = where the needle falls into)

grz Thijs

 

it's completely relevant because an issue that is in a certain rpm range will act the same in any gear. not just those gears. I would check the plugs wiht a plug chop and then the floats.
what happens if you lay into the throttle while it is surging?

 

From my dyno tuning days on Carbureted bikes, I believe that the 5-6k rpm range would indicate a needle issue. You said that you have one washer under the needle. Is this stock?

IF it isn't a stock set up, I'd remove that washer and go from there. I remember toying with my 99 F4 and having a lean spot after moving the needle clip down one and it performed like a pig. I moved the clip back to where it was originally, took the same ride and no more issue.

Anything higher in the rpm range (not by much) and I'd be looking at the main jets.

 

This will make them rch, and yes the same generation of mikuni's they slapped on GSXR's did that ... famous for doing it in fact, mine may have just too few miles for that and besides I am lean, not rich.

Helmet: It takes off like a shot when I open throttle when its surging. definetly lean. Not rich. Now its really not tied to the rpm range, its tied to throttle position. However in 3-4 I am at 7K and its so touchy atthat high rpm that it really is hard to tell. Carburetion problems - especially the subtle ones show up under high loads only. I have done over 300 carbs most of them gs500 ones ... this is carburetion, its lean and its lean on the needle. I will plug chop yes ... but really I could fix it first then do a throttle chop/plug pull to be sure.


Mcrtw644: the needle has been lifted with the washer, removing washer makes it leaner. I am referring it as it is in a running bike. Moving the clip down 1 notch will lower the needle and hence make it leaner.

Like I said, I have done a 300+ carbs on gs500's mostly, and this is the same style. My actual question is, has any one else had this happen and did you put more than 1 washer under the needle's E clip.

I guess I try it and post back if no one has. I dont have a problem there, I got washers, I do jet kits for GS500 and the same wahsers work on these too.

Cool.
Srinath.

 

I'm wondering, do you have pods on it? what about an aftermarket exhaust. Not sure how familiar you are with these bikes, but it's many people's experience that if they are rejetted and have pods/aftermarket exhaust on them, they run like crap. I had one maxim xj700 air head that just had mac exhuast on it and it still runs like crap. I hate those aftermarket exhausts. I'd rather put a stock exhaust on these puppies anyday....I digress, and vent, sorry

 

I agree with a low mileage on the bike the tubes can't be worn, and yes, it indeed makes the bike run rich. But just for reference, at my RF the tubes were worn within a little as 12 dkm. (about 7500 miles) My mate/mechanic with the dyno didn't believe me either until I showed him the tubes .

Have you synched the carbs recently?


grz Thijs

 

mcrwt644: Its all stock, 100%, no pods, stock airbox with clean filter and stock pipe. I can put a pipe on it and pods on it and jet it in 2 tries or less without a kit. Seriously, that airbox and filter design and pipe exactly are good for +8-10 sizes on the mains ... as in if it has 125's, next up from 125 is a 127.5, so its is 1 ... 10 sizes up form 125 will be 150, and that is the number I would use if it was 125 to begin with - dont remember.

I am just seeing if anyone has has a need to put in an extra washer - AKA, 2 washers toital under each needle ...

Thijs_205_rallye: RF is down draft ... suzuki did many many mistakes on that one, and this was just 1 of them ... you dont slap the crap you put on a side draft head onto a down draft head. Huge boo boo on a bike that was intended to become the next katana and dethrone the VFR.

The carbs are synched and by eyeball, and its way better than vacuum synch and even if they were not, they wont affect 1/2 throttle unless they were waaaaaaaay out, and in that case, they will misbehave like a crate full of baboons at idle.

Like I said, I am looking for 1 specific solution to a very well defined symptom.

It is lean on the needle, almost nothing else matters. (unless it is float level or main jet). I am looking for someone who has had this problem, and has solved it by 1. washer under needle. 2. +1 on main jet. 3. Raising float level 1mm or 2 mm over the float bowl gasket level.

I have worked on this bike for 4 years now. I have worked on bikes in general for over 10, and I have done over 300 sets of carbs, 250+ on gs500's (which is a similar carb set to the water cooled maixm's BTW) ... and this is my second maxim I have owned - first was air cooled, and the third I have worked on, it was owned by a friend who lost it in a fire.

I am going to put washers under the neeldes in a day or so unless somene tells me otherwise ...
Cool.
Srnath.

 

have you checked for air leaks around the intake boots? high rpm can bring out strange symptoms.
i would look over the boots and fill any cracks with black rtv.

 

No leaks at idle, cant check at 1/2 throttle 5K rpm obviously ... I should have a dyno ... then I can check that ... but sadly no.

Boots and what not are good.

Its not much else other than a lean as Lindsay Lohan factory setting on the needle and much of the rest of the rpm range too, but definetly needle.
Cool.
Srinath.

 

I know you cant really check for leaks at 5k under load, but a small pinhole or bad gasket around the boot will cause some weird things to pop up.
I would check the seal around the boot and visually inspect the boots very thoroughly. any crack may appear minor and not causing an issue, but it could be the root of all your evils.
what is the condition of the throttle shaft seals?

 

The boots are perfect and they all have the largest likelyhood of acting up at low revs. Idle is where it makes the best vacuum. Anyway its getting washers tommorow.
Cool.
Srinath.