KLX250S (EFI) Big Bore Kit

[rickypanecatyl]

Just curious if there was any progress stories out there tuning the BB 351 with FI?

FWIW I now have well over 100,000KM on my BB351 cc kit here in Malaysia. The bike itself has about 200,000 KM. I am thinking of selling it and getting a new one. Mine is 2008 (like the US 2007 but with KLX450 speedo) and is carbed. The new ones are of course FI.
The bike has never let me down, but at the same time as it gets older I'm finding it's hard to maintain it to be running at 100%. Something is always close to needing replacement... swing arm bearings, frayed wires, leaking seals, blown shock etc. I've never got the BB TM 33 to 34mm jetting down very well and my mileage is horrible as well as it runs pretty rough at higher rpm's. Super tough to gets jets here, I'm not that clever with that sort of stuff nor do I have much time and while the mechanics here can afro engineer anything and get it running fine tuning isn't there specialty.

I'm on the fence between getting a new bike and putting a new 351 on or doing a complete rebuild of the old one. If there was one mechanic you know of in Bangkok who could do an excellent job of dialing in the FI with the 351cc I'd be happy to take a ride up there and leave it with him.

Any thoughts?

 

[TonyBKK]

I'm not aware of any fuel injected 351cc KLX's

As I understand it the stock fuel injector, even if tuned to maximum, can not supply enough fuel for 351cc.

I imagine one could install a higher capacity injector, but I haven't heard of anyone going down that road. I would wonder if the stock fuel pump provides enough pressure for a higher flow injector?

One of the big advantages of going with a carb is it allows you a much larger aftermarket tank.

I imagine range must be very short on a 351 with tiny stock tank...

As far as having your Mikuni TM33 tuned here in Thailand, I don't think there are many mechanics here who are familiar with this carb, so probably best to try and figure it out on your own. That's what I've had to do!

 

[KLX331 Crazy]

Bozza;296067 wrote: I have started purchasing all the parts needed to make my KLX250s(D-Tracker 250) into a 331 monster here in Bali.

Are any of the BB331 veterans here inclined to share their PCV map for the EFI. I would really appreciate it.

I am planning on running KK331, Beet injector, web cams 101, PCV + autotune, FMF Powercore 4 with megabomb.

Cheers,

Beau

Hi Beau,

I am running a similar setup but using Kustom Kraft cylinder and Beet cams, same exhaust with mega bomb. If you want I am willing to share my maps. Forget to mention its a KLX250S, not a D-Tracker

 

[niro28]

Hi klx331 Crazy!
I have just installed bb 331 kit with autotune and pcv and have this problem...
Can you please give me some more info about adjusting the throttle position sensor

Thx in advance!

KLX331 Crazy;277161 wrote: Gents, just a bit more information with the installation of the PCV and AutoTune units. Initially had a major problem with the bike hesitating and running ruf just off idle, thought that it was the PCV unit that was causing the issue. Found out after much thought and experimenting that it was actually the throttle position sensor that was causing the issue. The standard setting allows the butterfly to open without injecting fuel thus the bike leans off and in some cases will actually stall. Just adjusted up the sensor, so when the throttle is openen of the stop then fuel is injected, everything works perfect.

This is a common problem that I see with many KLX riders, bike stalls when coming off idle, check the throttle sensor adjustment and this will fix the problem. I used the PCV and software for adjusting the sensor but others may have to get a proffesional to check the adjustment on there bike.

Cheers and good riding.

 

[niro28]

Hi all! Can anyone give me some detailed info about adjusting TPS? I have installed BB331 kit + PCV&Autotune. Everything is fine except this problem

KLX331 Crazy;277161 wrote: Gents, just a bit more information with the installation of the PCV and AutoTune units. Initially had a major problem with the bike hesitating and running ruf just off idle, thought that it was the PCV unit that was causing the issue. Found out after much thought and experimenting that it was actually the throttle position sensor that was causing the issue. The standard setting allows the butterfly to open without injecting fuel thus the bike leans off and in some cases will actually stall. Just adjusted up the sensor, so when the throttle is openen of the stop then fuel is injected, everything works perfect.

This is a common problem that I see with many KLX riders, bike stalls when coming off idle, check the throttle sensor adjustment and this will fix the problem. I used the PCV and software for adjusting the sensor but others may have to get a proffesional to check the adjustment on there bike.

Cheers and good riding.

 

[TonyBKK]

The installation instructions that come with the PCV explain how to reset the TPS. Don't have them handy but it's quite simple. Probably you can find them also on the dynojet website?

 

[niro28]

Hi Tony, I thought it's about rotating the tps on the bike )

Actually now i understand that i'm running lean on any rpm and it is very sad... i cant understand what is the problem. My map is already heavely trimmed, even on idle with 0% throttle autotune suggests +40 trim in order to have 14 AFR. If i start to increase rpm i see AFR 15-16 (on trimmed map!!) Even 16+ so that autotune cant work under this condition (it works only if AFR <16)

I checked intake and exhaust leaks twice, i even cleaned the injector... no result. I'm confused and would be grateful for any advice

TonyBKK;302110 wrote: The installation instructions that come with the PCV explain how to reset the TPS. Don't have them handy but it's quite simple. Probably you can find them also on the dynojet website?

 

[KLX331 Crazy]

niro28;302117 wrote: Hi Tony, I thought it's about rotating the tps on the bike )

Actually now i understand that i'm running lean on any rpm and it is very sad... i cant understand what is the problem. My map is already heavely trimmed, even on idle with 0% throttle autotune suggests +40 trim in order to have 14 AFR. If i start to increase rpm i see AFR 15-16 (on trimmed map!!) Even 16+ so that autotune cant work under this condition (it works only if AFR <16)

I checked intake and exhaust leaks twice, i even cleaned the injector... no result. I'm confused and would be grateful for any advice

Hi niro28, have you blocked off the PAIR valve?? If this is not blocked then you will get fresh air into the exhaust system and the AFR will be lean.

 

[KLX331 Crazy]

KLX331 Crazy;302121 wrote: Hi niro28, have you blocked off the PAIR valve?? If this is not blocked then you will get fresh air into the exhaust system and the AFR will be lean.

Hi niro28, the PAIR valve is part of the pollution control and allows fresh air into the exhaust to help to burn off the unused fuel that exists the exhaust system. It is located beside the cylinder head exhaust port and has to small bolts holding it to the head, I had a plate made to blank it off but one of the other guys just filled the valve with silicone. If you use silicone remember to give it time to set before starting the engine. Hope this helps

 

[KLX331 Crazy]

niro28;302117 wrote: Hi Tony, I thought it's about rotating the tps on the bike )

Actually now i understand that i'm running lean on any rpm and it is very sad... i cant understand what is the problem. My map is already heavely trimmed, even on idle with 0% throttle autotune suggests +40 trim in order to have 14 AFR. If i start to increase rpm i see AFR 15-16 (on trimmed map!!) Even 16+ so that autotune cant work under this condition (it works only if AFR <16)

I checked intake and exhaust leaks twice, i even cleaned the injector... no result. I'm confused and would be grateful for any advice

Hi niro28, the PAIR valve is part of the pollution control and allows fresh air into the exhaust to help to burn off the unused fuel that exists the exhaust system. It is located beside the cylinder head exhaust port and has to small bolts holding it to the head, I had a plate made to blank it off but one of the other guys just filled the valve with silicone. If you use silicone remember to give it time to set before starting the engine. Hope this helps[/QUOTE]

 

[niro28]

Hi Crazy, thx for reply!
PAIR valve is blocked since 250cc.

Today i cleaned all the wire clamps with contact cleaner, tightened exhaust clamp, even checked my pair valve hose still blocked... no result
to lllustrate that's how my map looks now:

as you can see it's heavily trimed and still have high AFR
I did not check my compression after the installation, because i have no compressometre. I think i should find it and check

KLX331 Crazy;302123 wrote: Hi niro28, the PAIR valve is part of the pollution control and allows fresh air into the exhaust to help to burn off the unused fuel that exists the exhaust system. It is located beside the cylinder head exhaust port and has to small bolts holding it to the head, I had a plate made to blank it off but one of the other guys just filled the valve with silicone. If you use silicone remember to give it time to set before starting the engine. Hope this helps

[/QUOTE]

 

[TonyBKK]

Your map looks a bit crazy mate... I recently built a Kustom Kraft 330 KLX for a mate and didn't have to add nearly as much fuel as you have to reach target AFR. I'd share my fuel map created using an auto tune, but it's on my laptop in Thailand and I'm in the US right now.
No idea your location but the tool shop next to Veera Siam in Khlong Tan, Bangkok sells compression gauges for just 900 baht. I'd say you should definitely check your compression as something isn't right. A leak down test might also be in order but no idea where to buy a leak down tester in Thailand...
good luck!

 

[niro28]

Tony, can u tell please what compression reading should be on 331cc? Won't the KACR fake the readings?

 

[KLX331 Crazy]

niro28;302125 wrote: Hi Crazy, thx for reply!
PAIR valve is blocked since 250cc.

Today i cleaned all the wire clamps with contact cleaner, tightened exhaust clamp, even checked my pair valve hose still blocked... no result
to lllustrate that's how my map looks now:

as you can see it's heavily trimed and still have high AFR
I did not check my compression after the installation, because i have no compressometre. I think i should find it and check

Hi niro28, where is your O2 sensor mounted in the exhaust system and are you running the Beet oversize injector? What is your target AFR table set to?

 

[niro28]

Hi! idle set to 14, and 13.5 for 2-100% tps. Lambda mounted before muffler, same place then in stock. And it worked good on 250cc. I'm pretty sure now that the problem is in faulty installation, but i don't know what exactly... i used new torque wrench, everything according to manual and DIY guides. Rings were oriented properly, timing was good..Theoretically what can cause running lean? Bad gasket? I think first step i'll test my compression, then acording to results i'll start disassembling

 

[KLX331 Crazy]

niro28;302150 wrote: Hi! idle set to 14, and 13.5 for 2-100% tps. Lambda mounted before muffler, same place then in stock. And it worked good on 250cc. I'm pretty sure now that the problem is in faulty installation, but i don't know what exactly... i used new torque wrench, everything according to manual and DIY guides. Rings were oriented properly, timing was good..Theoretically what can cause running lean? Bad gasket? I think first step i'll test my compression, then acording to results i'll start disassembling

Hi niro, I would check your inlet manifold gasket / oring for correct fitting and the throttle body for air leaks. I don't think you have an issue with compression. When you removed the original O2 sensor, did you insert the bypass plug into the original O2 sensor connector?

 

[niro28]

I didn't touch the inlet manifold, i think there is a gasket only between manifold and Head... And i have O2 bypuss plug inserted. Anyway i'll try to check at weekend!

What do you mean "throttle body leaks"? I tried to listen for any leaking sounds. did not find anything... I checked all the clamps - everything was good

Thx for trying to help

KLX331 Crazy;302152 wrote: Hi niro, I would check your inlet manifold gasket / oring for correct fitting and the throttle body for air leaks. I don't think you have an issue with compression. When you removed the original O2 sensor, did you insert the bypass plug into the original O2 sensor connector?

 

[TonyBKK]

niro28;302140 wrote: Tony, can u tell please what compression reading should be on 331cc? Won't the KACR fake the readings?

As far as I know compression should remain the same with the Bill Blue 331 (which is why you don't need to switch to high octane fuel) but you're right that the compression release on the exhaust cam will make it challenging to get an accurate reading. You can remove it, but it would add a fair bit of work to your troubleshooting...

 

[TonyBKK]

niro28;302154 wrote: I didn't touch the inlet manifold, i think there is a gasket only between manifold and Head... And i have O2 bypuss plug inserted. Anyway i'll try to check at weekend!

What do you mean "throttle body leaks"? I tried to listen for any leaking sounds. did not find anything... I checked all the clamps - everything was good

Thx for trying to help

A manifold leak could certainly explain the lean running engine. Are you 100% sure that the o-ring that seals your throttle body to the head is correctly seated? That's given me problems in the past! Certainly before you pull the head off best to check the "simple" stuff first! I don't think you'd be able to hear a leak with the engine running...

Here's a very easy way to check for intake manifold leaks, shown on a car, but this test will work just fine on your KLX intake manifold too:

 

[KLX331 Crazy]

TonyBKK;302157 wrote: A manifold leak could certainly explain the lean running engine. Are you 100% sure that the o-ring that seals your throttle body to the head is correctly seated? That's given me problems in the past! Certainly before you pull the head off best to check the "simple" stuff first! I don't think you'd be able to hear a leak with the engine running...

Here's a very easy way to check for intake manifold leaks, shown on a car, but this test will work just fine on your KLX intake manifold too:

Niro, when you removed the head, you had to remove the throttle body from the inlet manifold, make sure that it has been reinstalled correctly otherwise there may be an induction leak there. Also try tuning without the air filter installed.

 

[niro28]

visually everything on its place, clamps are tightened. Today i sprayed some carb cleaner on junctions as shown on video - no result.
I think i'll test my compression, then remove cam cover to see what's going on there

 

[niro28]

Hi everyone!

Yesterday i checked my compression - 149 psi!!
Now i'm pretty sure that the problem is in my fuel sprayer..

Also i checked my service codes but i have problems with reading it. Can anyone help me? ) Is it 12??

 

[KLX331 Crazy]

niro28;302322 wrote: Hi everyone!

Yesterday i checked my compression - 149 psi!!
Now i'm pretty sure that the problem is in my fuel sprayer..

Also i checked my service codes but i have problems with reading it. Can anyone help me? ) Is it 12??

Hi Niro,

Did you remove the secondary butterfly and rod from the throttle body?? Inside the throttle body (carb) there are 2 butterflies, the primary and secondary, the primary has the throttle cable connected to it and the secondary is operated by a samll servo motor. if the rod has been removed for the secondary then the FI light will show an error code and the fuel injection will go into limphome mode (will not inject full fuel). I noticed from your video that I could not hear the servo motor working. If removed, reinstall the rod into the throttle body, be careful to make sure it is syncronised to the main butterfly. When you turn the key on you should hear the servo motor cycle and the FI light will go out. Once this is done, run the engine and recheck the autotune maps.

With the FI light is showing an error code, you will never tune the engine.

 

[heilong]

niro28;302181 wrote: visually everything on its place, clamps are tightened. Today i sprayed some carb cleaner on junctions as shown on video - no result.
I think i'll test my compression, then remove cam cover to see what's going on there

Don't use carb cleaner anywhere near rubber parts, if you still care about them! It's not safe for plastic, either. Brake cleaner is much milder to rubber, but not great either. Starting fluid or WD-40 would be safer to use for this kind of test.
That's why when you use carb cleaner to clean carbs or parts, you should completely tear down the carb / remove all rubber and plastic parts first!

As was already suggested, try take off the throttle body holder (the plastic part bolted down to the head) and check the condition of the o-ring. According to the manual, this o-ring should be replaced with a new one on reassembly. When I did a top end rebuild recently, my old o-ring had a little damage on it, I've heard from a mechanic friend before in this area you don't want any damage or wear whatsoever, he said just replace it if any doubt. Put a thin coating of grease on this o-ring as well (according to the manual).

 

[niro28]

Hi guys, I'm back with my "lean" problem =)
Does anyone have proper PCV map for 331cc?