I need top end!!!

[rhandw69]

Besides the Main Jetting, what other factors tie into your bikes overall top speed?
Since installing the 416, ive really lost my top end. Ive tried jets from 155 up to a 170 and still the same result.
One thing I notice is that it appears that when in top gear, the bike could use another gear, so now Im wondering how it would work if I install a 16t sprocket on the front rather than the 15.

Thanks
Rhan

[Atomic83]

Going up a tooth on the sproket will help, but changing the jets won't.

[mikeboone]

Like Atomic said; The ONLY way to change your top end speed is to change the sprockets, change the rev limit, or change rear tire size. Only other way is to actually change ratio of 5th gear with a diff. ratio gear. You must be not pulling to the stock CDI limit or your top end would be the same as before. You can expect a few mph gain going to a 16 tooth sprocket. As I have stated in previous posts; it doesnt matter if you have a 465 ex ; it will NOT have any more top speed than a stock 400ex assuming you do not change any of the above---Hope this helps some clear up some members "wishfull thinking" ~~~~ Mike

[nakomis0]

You CAN change your top end by adding a bigger carb or cam. Not many 400exs can pull 5th gear to its max. I carb and/or cam will help you do this.

If your can pull a 16 tooth that will work too.

[Chef]

with your 16/36 gearing nakomis can you pull the rev limiter in 5th? cause i can hit my white brothers one very easy with stock gearing

[mikeboone]

I could easily top mine out stock also--if he is hitting the rev limiter(likely) more power will not help``

[rhandw69]

Then why does it cut out and pretty much shut down as far as speed and power goes after 3/4 throttle?
My mid to top has been long gone ever since the 416 installation.
Thanks
Rhan

[NVR2L8]

Rhan, it sounds as though you still don't have the jetting right after doing the 416cc mods. Give us a little more info as far as what you did to the engine, such as what internal mods you did, what carb you're running, and whether or not you've modified the intake and exhaust system--once we have this info then maybe we can guide you in the right direction. I also have a Word document on carb jetting that I converted from a link someone posted here a while ago...it's really helpful in understanding how jetting works. I can send it to you if you want it. Also read up on how to do a plug chop and how to properly read a plug...that's the only way you can test to determine if you're running rich or lean. BTW, if/when you start testing the jetting, consider running a 3:2 blend of 92 octane and leaded race gas...that's the only way I could get a decent plug reading due to all the additives in unleaded California gas.

it's got to be jetting..also did you put in a new cam with the 416..if not gt thunders cam will add top end ..i am told

What's your motor tellin ya.....any backfiring,,,bogging,,,any signs,,of fuel/air problems.:confused:

[rhandw69]

I left the stock carburetor on, rite now i have a 170 main jet in, 42 pilot, my clip in in the middle. My exhaust is a WB E slip on, stock header. Stock cam, and a K&N filter with no airbox lid.
This past labor day when i had it at the beach, i had a 155 main jet. It ran hot, and my plug was pretty white. Still not much mid to top.
Through out the weekend i tinkered with the 155 through the 160. Still no top end.
However, when i ran the 155 all the way up to the 160, my top end never cut out and bogged once after 3/4 throttle. It only started that after i put in the 165-170 jets.
So i had FlyinRed ride it with the 162 jet.
He noticed that when takin off it popped and bogged when really getting on the gas from 1st gear to early 3rd.
Later my neighbor rode it once i got home and he noticed the same. What he thought was that my engine just needed more fuel. Thats why i put bigger jets in, now its boggy from mid to top.
Not to start anything negative here,
but realistically, my bike should be faster if not quicker than before the bore, or even just a plain stock non modded bike.
This however is not the case now.
I talked to Terry at Marcums, and he said that my bike should be perfect with a 170, 42 pilot, and clip in the middle.
I hate to give it to the shop to fix, but i almost think i need to now.
Thanks for the help
Rhan

Have ya adjusted your air mixture screw??

[Wheelie]

The 170 main jet is too rich. A 160-162 should be close to spot-on for jetting. Put your 162 main jet back in, set your air/fuel screw at 2-2 1/2 turns, if it doesn't run up to par, try some higher octane fuel.

Also, when you pulled out your main jet, did the brass tube come out at any time? If it did, there is an adjustment nut on it that if moved, would have the same effect as moving the clip on the needle, therefore greatly affecting the tune of your bike.

BTW--What comp ratio are you running.

[rhandw69]

10:8:1 piston.

Im going to recheck my timing chain and cam alignment, because even with the smaller jet,
it was slow slow slow.
Great torque, great power band hit,
but then thats pretty much it.
Rhan

[FlyinRed]

I think It's time to sell me the bore kit and put a 900cc snowmobile motor in her.