Still problems at 5500 rpm!!!!

[ride314]

Mains changed to 147.5 today. Still stumbles badly at 5500 rpm. Low end power is awesome and after about 8 seconds of stumbling, I am able to nurse it into the higher rpms then...hold on!!! 115 mph when I shut it down (got scared and ran out of room).

V-boost is still disconnected and in the off position. I am begining to think the "Keyster" brass is causing me the problems. Also have not changed the jet block gasket which is also "Keyster".

If it is the brass...which ones are giving me the problems, where to start???

All the stock stuff is gone (don't ask) and I am trying to not spend my whole paycheck buying jets.

Help!!!!

 

[maleko89]

I think the Keyster jets and needle jets are fine. I wouldn't trust that jet block gasket though. For needle jets, just take a magnifying glass and make sure the ends aren't oblong.

 

[ride314]

Cool...I will start with changing the jet block gasket back to OEM and checking the needle jet.

I really want to do one change at a time but I am getting real tired of removing and installing the carbs.

Getting pretty quick though!!!!

Thanks for the reply.

Just for clarification cuz I am a retard, the needle jet is the jet the needle slides into?? My needles are stock.

 

[one2dmax]

You might be able to try and shim the needle first and see what that does. Simple to do and can at least tell you if it works or makes it worse.

Sean

 

[ride314]

Again, I am a retard, what will shimming the needles tell me? If it helps does that mean the needle jet is not to specs?

How much should I shim them to start?

Thanks.

 

[maleko89]

Correct, that's the needle jet.

To shim needles you put a thin washer between the needle e-clip and nylon needle retainer. It raises the needle and fattens up your midrange.

 

[4gasem]

I'd try shimming first! One washer and go from there...

 

[Rhoy Carter]

I had a simular problem on a Vmax a couple of years back and it turned out that the timing advance was not working.

 

[dlopes]

I'm having the same problems. I just installed Sean's jet kit and put a kerker 4:2:1 on with a CF can. I used the 160's at first. I was having problems all over the midrange and was bogging a tiny bit at the top. I then went to 157.5 main jets. Same problems in midrange, but top cleared up. I had some stage 1 needles (see http://www.vmaxforum.net/showthread.php?t=3208 for needle info) and installed them to play with the needle depth. The middle or 3rd slot setting on the needle is just a hair shorter than the stock needle length. Started with the 3rd slot setting I had the same midrange problems. I went to the 4th slot from the but end and now I am only having problems at the 5500 to 7000 range. I ran out of time, but I am going to try the 5th setting tomorrow. I'll let you know the outcome.

 

[dlopes]

OK, I just went to the 5th/last slot setting from the but end of the stage 1 needles and she screams from dead stop to red line at WOT with NO hesitation at all. Even with a slow pull all the way up is clean and hard. I have tried it cold and full operating temp. The 5500 blues are gone!!!!!!!

Ride314,
First off, make SURE that all of your carbs are CLEAN and all of the tiny passage ways are blown out with compressed air or you can use cans of carb cleaner, but carb cleaner can get expensive. The first time I cleaned my carbs, I went though about 12 cans of carb cleaner at $3 a pop.

Very important........After carbs are clean, ensure float levels are set. I know everyone has their own distance settings for float levels, but there is only one way to get them perfect. Use gas and get the no shit level height. I am going to write up a thread with some pics and instructions on how to measure your float height with gas MacGyver style when I get time. In the mean time, for my carbs after I set the float levels perfect with the gas set up, I measured the distance of each one. One was dead on at 16mm, one was at 16.3mm, another at 16.4mm, and the last was at 15.8mm. So pretty much around 16mm will get you close to perfect. You will never know if they are perfect until you use the gas method. If you want a leaner mixture, go to 17mm and for a more rich mixture, go to 15mm.

After your floats are set and your carbs are assembled, get them on the bike and sync them. There are great threads on carb rebuild and carb syncing on here. Just look in the carb section.

If you have done all of this and you are sure of your cleanliness and float levels, than I suggest getting a set of adjustable stage 1 needles or buying some washers to shim the stick needles to the correct depth and get rid of your 5500 RPM blues. Don't worry about the main jets unless you have problems from 7500 and above. It sounds like you have the correct ones installed.

Before you start tearing apart the carbs again changing out gaskets and brass, try the shimming or new stage 1 needles. The adjustable stage 1 needles will take the shimming out of the picture.

If you are unsure of how to do any of this, just ask and I assure you someone will help you out. Just to warn you, you might have to use a bunch of shim washers to get to the correct needle depth. Let me know if I have left anything out.......D

 

[ride314]

Thanks for the input. I will be working on it this weekend.

 

[veebooster]

Jumping in on this.....mine would break up consistently at 6000rpm. Ended up with shimmed stock needles and a bigger main. I like it now!!!!!:eusa_dance:

Dale #2592

 

[hatley]

This sounds like what I have going on bike is flat till I get rpms to 6000
the bike runs good but I rode a different max last weekend and what a difference. his is a rocket!
This forum is great, any good vmax mechanics in wisconsin anybody know of ? thanks hatley

 

[ride314]

Changed the Keyster gaskets last weekend. They were all messed up....I don't think the jet block could have possibly been seated correctly with those crappy gaskets.

Got everything back together.....Now it won't run off of idle at all....I am about to send the bike on a long trip off a short pier (if I can get it to run long enough).

I set the floats to 1.125 and I think it is way to lean. I am going to richen it up a little and try again. I am also going to check the timing advance as recommended here. I checked the needle jets and the holes appeared to be good.

Beyond frustrated!!!!!

 

[one2dmax]

It idles but not revs? You have the airbox on and firmly sealed up on the carbs?

 

[Rusty McNeil]

just a tip, perhaps not relevant to your situation.

Whenever putting the needles back in after shimming always make sure they "wiggle" freely in the slides.

If they won't wiggle a little bit they will eventually hang up on the sides of the needle jet and inhibit movement of the slides.

Rusty

 

[veebooster]

just a tip, perhaps not relevant to your situation.

Whenever putting the needles back in after shimming always make sure they "wiggle" freely in the slides.

If they won't wiggle a little bit they will eventually hang up on the sides of the needle jet and inhibit movement of the slides.

Rusty

Very good point!!

Dale

 

[mdix1]

Did u use the keyster nozzle jet brass. the part the needle goes in that the jet block goes over? If u did itmay be the problem it doen't line up like the stock one does with the jet block.