tuning the topend on the top of the motor ill try that, I had no power

last glow plug!, ill try it all put a new filter on, fatten it up this also happened with the trax plugs for the 3.3 im using with 30% I blow 3 plugs in a hour

Hi just wanted to some advice on tuning, I have used the tuning guide on massive mods and had my gx-5r about a month now (but not much racing due to bad weather)

My idle is set up fine and I have tuned the lsn and hsn, the power from stand still is amazing and have good trail of smoke all the way to top end.
I can do many practise runs and have no problems and then once i finish a full throttle run, it bogs for about a second then its fine. The sound of engine seems like it wants to go faster but unsure why it keeps intermittently bogging from a long run

any ideas, do you think i could be do lean at the top end ?? Thanks

I usually just keep it simple, on 30% after a gallon take out one thin brass shim so it has one alum and one thin .1 mm (.004") brass. If running 20% just run the aluminum shim, why does MM have to confuse so many people?
The best way to check head clearance is to use a caliper and measure it. Measure the head button down from the cumbustion chamber to the shim stack. Then subtract the measurement from the top of the sleeve to the piston at Tdc. You should get from .026-.030 or .7mm.


Rex

Bummer !! What plug are you using ?
Fatten up the the top end until it is too rich and then work your way back until you have good performance with a good smoke trail right through the rev range. If you richen the top signifigantly you will need to lean the bottom some to compensate. Check the idle gap also. If it's too wide (greater than .7 mm) this could be causing you to run the top too lean in order for the motor to perform down low with this wide idle gap (causing rich bottom end). Check and set the idle gap before you do any tuning adjustments. If it won't idle with this gap, then lean the botton end until it will idle, but don't increase the idle gap to keep the motor running.

If your running 30% with a hottish plug your tuning needs to be pretty spot on.

just for a reference,when you take out a shim,do you have to lean the needles or richen?...was just wondering cause im going to remove another shim!

+1 on that.
Motors run sweet as with that set up on 30% with OD97T plug or similar. Still easy to tune, with a nice steady idle.

Does it sound like it wants to stall just after you have come off the gas and the revs drop, or is it hesitating when you get on the gas again after a WOT run ?

You probably won't notice too much difference. Just run it and re-tune if you need to.

ok cool!...i tried 2 copper .2mm shims and it was great!...now im gonna try just 1 alloy .3mm shim and see how it screams!...i run 20% and od77t plugs!....has any1 ever tried the OS P7 medium plug?

It sounds like it hesitating for a brief second and then clears and then fine, I was not happy with my original tune so I started again from factory settings and now the low power band is 10 times better than before and the car seems to fly with plenty of smoke. Just wondered if was due to WOT for a short while.
The engine is still pretty new and I am only on the second plug running 25% so overall I am very pleased with it

May be just a whisker lean on the top end. Give it an hour richer and see if that gets rid of the hesitation. If it's pretty new it may still be a little tight, and too lean on the top may cause a little lean bog. Check your fuel lines and tank lid seal etc for any leaks too if richening the top end doesn't solve the problem.

Ok many thanks, the hsn is very sensitive

fatten it, and it worked just fine didnt blow the last glow plug im a great painter but the worse tunerwhen it comes to low end thats the screw om the side
Thanks

now thats more like it