Campy

My Feedback: (1)

My Saito 80GK has had the following done to it:

Valves adjusted to correct clearances and rechecked.
Needle valve/spray bar upgrade installed.
Intake gaskets replaced (part of needle valve/spray bar upgrade kit )
All fuel lines, including lines inside the tank) replaced
All engine bolts double checked for tightness.

The Problem:

The engines surges at 3/4 - full throttle.

My idle is 2550 - 2600 (low speed screw out about 3 1/8 turns ). The idle is not near as smooth as my Saito 72, 82 or OS 52 Surpass.

MAX rpm with a 13x6 APC and Powermaster 15% nitro is 8400 - 8575 rpm. (Should be in the 9500 - 10,000+ range )

High speed needle is out about 2 3/4 - 3 turns.

If this is any help, this particular engine trys to backfire a lot when starting compared to my Saito 72 and 82.

I have a gut feeling the low rpms and the surging are connected (but my gut has been wrong before )

Any ideas/suggestions ?

Thanks

P-40 DRIVER

Check your cam timing, sounds like your a tooth off, if of course, the engine has ever been taken apart.

alfredbmor

Well I had a kind of problem like yours; I bought on EBay a Saito 91 which was very difficult to tune up. After several months of experiencing with it, I definitively decided to change the carb assembly and the needle valve, I could fix the problem cheaper, with only the needle valve, what I found after is that the previous owner changed the original needle valve; of course it partially worked fine but never had the right in the spot point of tune. When I received the new needle valve I was curious and compared both, the old one was a bit shorter and wider, the new one was a bit longer and thinner, I have to say that physically there was a minimal difference but when installed and tuning, Boy what a difference!!.
Normally you open the needle valve 2 and a half turns, then you start to close to get the most rpm, with the old valve I had to open almost 4 turns and there were a big sweet spot between 2 and a half and 3 turns but always erratically, since you are in a similar situation I wanted to share this experience of mine that could be helpful.
Best regards
Alfred.

blw

My Feedback: (3)

You should be getting a lower idle. Backfiring is from a lean condition. Try richening the low speed needle valve about 1/4 turn for starters to get it rich enough again. Then, fine tune from there if needed. The adjustment is effective up to something like 80% throttle. It will have effect on the high speed setting.

The correct high speed needle valve setting could be anywhere. You can't use a specific amount of turns out to find the right spot.

Correctly setting the needle valves may solve all of the issues with the engine.

edited for grammar

Dave :^)

Hi,
you don't say what fuel you are using, if your '80 is a high compression one you may be using too much nitro.
Dave :^)

Whoops! sorry I see it now, haven't woken up properly!