losing compression limiting top speed? By jake aka:ventoscoot (Read 2,060 times)

[jake aka:ventoscoot]

Just a thought on trouble shooting my top speed issues. As an update, I have a 59mm top end, UNI filter, 28mm FS carb, NCY exhaust, and some trans upgrades (NCY teflon variator, 11g weights, NCY perf clutch). for whatever reason Ii am getting to 52 mph top end (gps) with 6200 rpms or so and it just hits a wall. gets there great, but that is it. I am wondering if i may be losing compression and that is what is stopping it. Any ideas all?

[jake aka:ventoscoot]

Just that way after the winter break. May have been the plug so I just put in a new iridium one today (old one was iridium but had 2k miles on it) I will check the breather. On the center stand I can wrap it up as high as I want to, don't take it past 8500 though. I also changed out my 6 pack of 14 gram rollers for a total of 10.5 grams. And the compression test I should do with it hot right? at least 200 degrees?

[jake aka:ventoscoot]

Compression is fine like I thought. checked on a couple of things, upjetted from 115 to 120, 12g rollers and an important one, the caps I had on the vacuum ports were al rotted and probably leaking. New temp caps on, and JB weld tomorrow! Should be able to ride tomorrow and will let you know!

[jake aka:ventoscoot]

cant take a pic of the rotted vac caps, I threw them out. Well, it was either the jetting or the rotting caps, because replaced the caps, and upjetted to 120 and the Punisher is back baby! GPS with full tuck, on a flat, with no wind, and made 67mph, will try to take a pic of the GPS screen next time, but it is hard in a full tuck. same flat, no wind, made 60 with a little left. Very happy. More importantly than top speed is the fantastic climbing. was able to maintain speed or gain speed on all of the hills around my house. None of them are really that big, but I am in no way a speed bump. Keeping up very well.

[Alleyoop]

Jake Aka:Ventoscoot,
I am having the same problem with my Trike. And I am hopeing it is the lack of gas at WOT. You have me hopeing for the best now:) I have tried everything weight changing, valve adjustment, performance coil, performance cdi, iridium plug adjusted the floats and now evern have a brand new carb and it still tops out at 6900-7000 rpms with 11G Sliders and it should be doing 7500 rpm or so and I am losing at least 5mph.

I have a K&N Cone filter coming this week and I will have to re-jet the carb I have no choice:)
Just like yours mine reachs 6900-7000 rpms and sits there and the last 1/4 throttle does nothing I was hopeing it was lack of fuel cause thats what it feels like. You have got my hopes up buddy.
Alleyoop

[Doug in San Diego]

Jake

Can you take pics of the vacuum caps? What are you capping? I only have 2 vaccuum lines, one to the carb and one to the "pump"

I'd just like to better understand your setup.

67- Pretty awesome

[jake aka:ventoscoot]

Here is a pic:
The circled area is the vac port on my intake. The arrow points to a vac port on my carb. The pink hose is for ilustration only as it is a flat slide and I have a manual shut off for my fuel line and gravity feed, no vacuum is needed. I had the two ports capped off with little rubber caps I bought at Checker auto for cheap. They were rotting and almost fell apart in my hand when I pulled them off.

Here it is installed, again with pink hose for ilustration and yellow circles showing ports.

Manual shut off:

Zip ties have since been replaced with quality hose clamps. If you look close you will see my mistake when putting it back together. The fuel is going into the "out" side of the filter. I have since re-run the whole fuel line down the right side of the scoot, stright to the carb. Cheers!

[matsalati]

I`m having a oko carb too. had to make a proper intake manifold myself and then it started work almost. any air leak from intake and it wont work. re-jetting is very important,to get it run right.
only difference is that I`m using 21 or 22 mm carb. because they say smaller carbs run good in low rpm`s too.
this vacuum line I put to the shut off fuel. and thats it.
have a far pics of mine to