K&N Filter & Jets = Follow GStwin Exactly

[crash]

ahh soo!

thanks for the link Kerry... i've read quite a few rejet threads and even googled, but i've never seen that page  

[danci1973]

Where to order Mikuni jets online?

As my engine doesn't like high RPMs (ie. above 9000RPM), I'd like to experiment with main jet sizes, so I'd like to get jets from 115 - 150 (in pairs).

I can't seem to get them from Suzuki dealers around here as they all want my VIN and then they order the 'factory default' jets...

Thx, D.

PS: My spark plugs have white-ish electrodes and isolator... That is too lean, right?

[Kerry]

My spark plugs have white-ish electrodes and isolator... That is too lean, right?

I can't help with the jets; I've been "ordering" them through other GStwin members.  :mrgreen:

As for the plugs, are they even whiter than the "Normal condition" sample on this Haynes Spark Plug Chart?

For a second opinion, read the SPARK PLUGS page from Dan's Online Motorcycle Repair Course.

[danci1973]

My spark plugs have white-ish electrodes and isolator... That is too lean, right?

I can't help with the jets; I've been "ordering" them through other GStwin members.  :mrgreen:

:dunno: Oh my...

As for the plugs, are they even whiter than the "Normal condition" sample on this Haynes Spark Plug Chart?

Yeah. Here is one:



and the other:

For a second opinion, read the SPARK PLUGS page from Dan's Online Motorcycle Repair Course.

I'm reading...  

Thanks, D.

[The Buddha]

Yup its lean... I have seen very very very pretty looking bikes that were so lean they wrinkled the front fender from the heat. Lean enough to have the pipes glow red... Maybe. You want jets, get 125's for a all stock bike, and if you made mods tell us what the mods are and we'll suggest the jets.
Cool.
Srinath.

[danci1973]

Yup its lean... I have seen very very very pretty looking bikes that were so lean they wrinkled the front fender from the heat. Lean enough to have the pipes glow red... Maybe. You want jets, get 125's for a all stock bike, and if you made mods tell us what the mods are and we'll suggest the jets.
Cool.
Srinath.

Now we're talking!

OK, the only mod I have is an open exhaust can - and I have that on because the bike actually runs better than with the stock one (stock exhaust somehow makes the bike run terrible at 6000-7000RPM and anything over 9000RPM).

With the open can the 6000RPM hole is almost completely gone, the bike feels stronger throughout 4000-9000RPM, but still doesn't like to go higher (but not as bad as with stock can).

Originally I had 125 (left carb) and 115 (right carb) main jets, together with slider travel restriction (yeah, my bike was factory restricted to 34PS).

I removed the slider restriction and replaced the main jets with 127.5's (in both carbs) so far, but I haven't noticed much of a difference.

I haven't done the float level (don't quite know how to) and I haven't synced the carbs - yet (don't have the equipment).

I have a pair of 130 main jets and 127.5/122.5 (Suzuki recommendation) I can try...

 Thx, D.

PS: I know my bike isn't running well as my top speed is only ~140km/h (~88mph - measured with a GPS and Sigma bike computer).

PPS: The 127 I use now and 130 jets were 'made' by a mechanic (actually, he took some smaller jets and enlarged them - I don't know if they are 100% what they should be...). And they have a smaller head than original jets.

[Kerry]

I haven't done the float level (don't quite know how to)[...]

See my Float Height page.  CAVEAT: This page tells you how to CHECK the level, but doesn't include the procedure to CORRECT it.

[...]and I haven't synced the carbs - yet (don't have the equipment).

You can get pretty close by using one of the "no fancy equipment" methods described in the How to sync the carbs? thread.  Especially read Srinath's and scratch's first posts and the later post by Lars.

I would almost swear that someone posted yet another "no tool" method recently, but I can't think of what to search on.  

For more info on "cheap tool" methods, see the Carb Synchronization ! thread.

[mjm]

[quote="danci1973]
Originally I had 125 (left carb) and 115 (right carb) main jets, together with slider travel restriction (yeah, my bike was factory restricted to 34PS)....
I removed the slider restriction and replaced the main jets with 127.5's (in both carbs) so far, but I haven't noticed much of a difference.

I have a pair of 130 main jets and 127.5/122.5 (Suzuki recommendation) I can try...
PPS: The 127 I use now and 130 jets were 'made' by a mechanic (actually, he took some smaller jets and enlarged them - I don't know if they are 100% what they should be...). And they have a smaller head than original jets.[/quote]

On 4 cylinder and on V twin bikes it is quite common for carb jets to differ - The inside cylinders or the back cylinders get different cooling air flow and they compensate by changing the jetting to reflect operating temperature.  I have never seen any recommendations, nor can I think of a justification for an air cooled  parallel twin to have different jets right and left.  Also, while it is possible to change the size of jets by drilling, there is a lot more to the flow of a viscous fluid through an orifice than the largest cross section of the hole - the most common effect of making the hole slightly larger would be to ruin the profile and reduce fuel flow - not increase it.  This could cause yur lean condition.  The way around the restriction is to drill a bigger hole - at some point the larger size makes up for the increased friction - or (so you know what is going on) get the right jets.

Your plugs are so white (at least on my monitor) that I would be very concerned about causing damage to the engine by running it --  You should know that the lean jetting causes high enough internal engine temperatures to cause your engine to sieze.  Now, if you did not pull these immediatly after a 10-15 second full throttle run followed by hitting the kill switch and coasting to a stop, it is possible that they just reflect your idle mixture - still too lean - but not a huge problem, just open up the mixture screws about 1/2 turn and try it again.  Then do the proper full throttle run and re-post pictures of what they look like then.

The 9000 rpm and up problem can be caused by a bunch of things that are not jetting related as well as things that are jetting related.  

Are you sure that the slides are free to rise all the way up in the carb bodies?  Are you sure that the little "o" ring on the top of the carb is in place?  Are you sure that the diaphrams in the carb are OK?  Are the valves adjusted properly?

GET PROPER JETS - PUT THEM IN If you have stock airbox and filter with the exhaust drilled start with 132.5 or so.  If you have K&N in the box make that 140.  These may be too big - take full throttle plug readings and adjust sizes as needed.

[The Buddha]

The smaller head jets ok Ed_in_Az recently tried them... and hated them... Look at post "Rejetting - Follow gstwin exactly" for more info. You need the big slotted round mikuni's, not the little slotted round mikuni's...
Cool.
Srinath.

[The Buddha]

Ok this is that thread    ... OK...  :dunno:
Cool.
Srinath.

[danci1973]

So far I have learned that I need to do valve adjustment... Even though I took my bike to the dealer a couple of times, I don't think this has been done.

Bigger/different jets are next - but where to buy jets? I called up several local (and not so local) Suzuki shops and they are all either stupid or unwilling to help.

Are there any 'online' shops, where one can order any number of any kind of jets?

  D.

[Kerry]

Ok this is that thread    ... OK...  :dunno:
Cool.
Srinath.

_I_ wasn't going to say anything....  

[Eightmarky]

I have done this and my bike runs sweeeeeet!  :mrgreen:

[mjm]

So far I have learned that I need to do valve adjustment... Even though I took my bike to the dealer a couple of times, I don't think this has been done.

Bigger/different jets are next - but where to buy jets? I called up several local (and not so local) Suzuki shops and they are all either stupid or unwilling to help.

Are there any 'online' shops, where one can order any number of any kind of jets?

  D.

Large round Mikuni main jets - order by size .  Almost any motorcycle or snowmobile or outboard  shop has a box full sitting in the back - does not need to be a Suzuki dealer. If the parts guy is an ass (and many are) try talking to a mechanic.   If none of your local dealers are cooperative try Bike Bandit, Ron Ayers, Dennis Kirk - petty much any on-line parts store.