Yamaha Tri-Z 250 85' - Just installed the K&N Need Help Jetting ?

[ceaserthethird]

Hey Guy's this is my First Time on Jetting ...

The old Stock Air Filter - Seem very Restrictive Dirty and full of oil

The Tri Z Has a - DG Performance Pipe & Stock spark arrestor / muffler .

I Just installed the K&N Air Filter

I Can Hear it Sucking tons of Air when i hit the Throttle

Now after i let it warm up i took it for a test Drive and on the Mid To TOP END it didn't feel like it was going any faster or reving any higher just bogged mid to top

As to Jetting i have no clue this will be my First Attemp ...

i'm in Portland , Oregon / The Altitude around my Area is Sea level to 400 Ft. in some area's...

Any Help Highly Appreciated

Trikes for Ever

[Dammit!]

If it's truly a bog and not a sputter, it's not getting enough gas. You should be getting a lot more air flow now so you most likely need to drop your needle clip (lowering the clip actually raises the needle allowing more gas to flow out of the jet) and go to a bigger main jet. Nobody can tell you exactly what you're going to need here. It's going to be up to you to do some plug chops and experiment a bit.

Now, if it's a sputter, that's too much gas in which case the opposite of the above needs to be done. It's hard to tell the difference until you've adjusted them too far in both directions.

And by the way, just changing the air filter is not going to make it any faster. It can give you a very subtle power increase but the real difference is throttle response. Once you get it dialed in it should be a lot snappier.

[jason 32]

did you oil the new filter ???/ there suppose to be gummy thats what collects the dirt---why the air filter?? what did it run like before??
is the plug wet??
bog could be too much fuel aslo
really there could be alot of problems,are the reeds ok,not warped or cracked?
rings good??
whats the air screw set at??,try 2 complete turns from completely closed
crank case oil seal good??
center case gasket good??
what does the plug look like,does it burn the crank case oil ( clutch oil)????
sorry, with out checking things out it could be ny thing

[ceaserthethird]

the Tri Z 250 Ran perfect untill i change the Air filter , Now it feel's off ...

[Yamaha Tri-Moto]

I would like to know the same thing. I just installed a K&N in my R which ran perfect before, now in the mid to high range it will rev up but not go any faster. I have a feeling its just not getting enough fuel. I think the only way to fix it is just to ride it and keep messing with the fuel air mixture.

[Dammit!]

You guys need to learn to jet and read plugs before you seize your top ends. All the information you need to do it is on this forum in multiple threads. Spend some time and figure it out now or you'll be figuring out how to rebuild your motor instead.

[Yamaha Tri-Moto]

I have already rebuilt a few top ends (Not by me blowing them lol) But As long as my trike is smoking blue smoke and the plug is a bit wet im not afraid to ride it and mess with the jetting at the same time. Plus I mix at 20:1 so im not to worried about blowing the engine.

[ceaserthethird]

Which jet's to Switch Main or Pilot ?

how many size's to buy ...

[willcamach]

lmao same problem here with my 250r and a k&n. jetting is such a pain in the arse when you dont know what you are doing. feels like a big guessing game.

[ceaserthethird]

- can someone narrow it down some , For the New Rider's ?

Like for instance - Go buy 2 main jet size up and 2 down , and 1 pilot up and 1 down or something ....

- someone with Same setup , post what you Did on tuning ?

[Dammit!]

You can never have too many jets laying around.

If your bike was running ok prior to the K&N being installed and now it's bogging mid to top, it's getting more air than fuel. Running it lean like that is VERY BAD. Running it too rich won't really hurt anything. Rich just makes them run poorly (they'll sputter when they load up on fuel). In my opinion, go rich until you know what's going on then go backwards from there just to be safe.

This is what I would do. Opinions vary greatly on this subject however.

Put a larger main jet in there. Minimum two sizes bigger. Maybe more. Drop the needle clip two spaces. Leave the pilot alone. Now do some test riding and plug chops. If it runs worse than it was before, you were likely too rich to begin with. No harm no foul. The plug will tell you exactly what is going on and this way you shouldn't be in danger of burning up the piston from being way too lean during your testing/plug chops. The only thing you should be concerned with during this stage is how it runs WIDE OPEN!

Get your main jet dialed in first as it effects the needle adjustment that you'll do afterwards. After it's running good at wide open throttle and the plug looks good after wide open plug chops, then it's time to dial in the mid-range with the needle clip. Just remember, lowering the clip RAISES the needle. Raising the needle is richer because it lets more fuel flow from the main jet. Lowering it leaves the needle in the jet longer which obviously reduces the possible fuel flow. It'll make sense once you take a good look at it. You can do some mid throttle plug chops if you want but I do this part mainly by feel. Adjust it up and down until there's no bog or spudder. The needle has no effect on wide open throttle performance. It's effect is between 1/4 throttle to 2/3 throttle. Performance problems in that throttle range can be adjusted out here.

You most likely won't even need to touch the pilot jet. Once the main and the needle are dialed, you can tune up the lower end with the air screw. Two schools of thought on that. One is to tighten it until the machine bogs, then loosen it until it bogs, then put it right in between those two points. I've always adjusted it by feel, looking for the best off idle throttle response. The pilot jet and the air screw only effect idle, throttle response and very low throttle performance.

[ceaserthethird]

AWESOME -

To thumbs up for - DAMMIT!

[Mosh]

i have been told the stock tri-z jetting was rich to begin with.correct me if i am wrong.my z is 60 over with a uni filter and stock mainjet.it runs real nice.i run 44 :1 premix.maxima 927.maybe he is also rich on premix if it bogs.

[ceaserthethird]

For the - Mix

Gas / Oil mix - i'm running - Honda SYN. 100% HP2 @ 32.1 with 92 Octane .

[Bryan Raffa]

I would lean the mixture out.. oil properties have come a long way since 1985 when the recomended ratio was 32-1...