Apex won't Idle

RX-1MT · Oct 24, 2009

Just rebuilt an Apex motor using wisco low comp pistons and still running a head shim with boondocker gt 28 now we can't get it to idle after about the 3000 rpm mark it cleans out and sounds great air fuel gage reads 16:1 to 17:1 at idle any ideas?
Thanks Mick

SPOOLED · Oct 24, 2009

your timing is out.

EZmoney · Oct 24, 2009

Check to see if your throttle cable is to tight.

zebiraross · Oct 24, 2009

No codes?

RX-1MT · Oct 24, 2009

No codes, throttle cable loose, and timing was on, there is just no idle anything over 2000 rpms is perfect has anyone else run low comp pistons with a headshim? All else fails I will check the timing again

big-zig · Oct 24, 2009

check for air leaks...

relentless rider · Oct 24, 2009

apex

is it had to start too? sounds like what mine was doing,i checked the timing and it was off a tooth,might not hurt to look:beer;This was with 0.63 shim with gasket on each side

HYFLYR · Oct 25, 2009

Hate to say it but it sounds like your timing is off. Been there done that, fixed a few for guys that had the same problem.

RX-1MT · Oct 25, 2009

Thanks everyone for the info, I was thinking timing myself just hate thinking of tearing back down but what do ya do, does anyone have any pics of the timing marks with a head shim?
Thanks again!!

POONSTALKER · Oct 25, 2009

big-zig said:
check for air leaks...

what he said:beer;

SPOOLED · Oct 25, 2009

RX-1MT said:
Thanks everyone for the info, I was thinking timing myself just hate thinking of tearing back down but what do ya do, does anyone have any pics of the timing marks with a head shim?
Thanks again!!

the marks on the cams have to line back up with the cam caps but you have to grind out the gears so you can line up the dots, have you done this or just put the shim in and tightened everything back up?

RX-1MT · Oct 26, 2009

yes the intake gear has been ground the sled ran with the shim set up for two season before taking out a rod bearing, we replaced rods pistons ect. and now it just won't idle once you let off the throttle it like you just shut the key off there is just no idle

SPOOLED · Oct 26, 2009

did you double check the timing? set the tdc on the crank, pull the valve cover take some pictures and please post them.

TurboKeith · Oct 27, 2009

I tried the low comps with a head shim a couple years ago; had my compression down to about 8.6:1. It ran fine at lower altitudes but the throttle response was pretty crappy at the 5000-6000 ft elevations. The fuel economy was pretty bad too.

RX-1MT · Oct 28, 2009

I think we are going to remove the shim let you guys know!!
Thanks again for all the help!!!

EZmoney · Oct 28, 2009

RX-1MT said:
I think we are going to remove the shim let you guys know!!
Thanks again for all the help!!!

Just wondering why you guys put the head shim in with the low comp pistons? Trying to run more pump gas or...

RX-1MT · Oct 28, 2009

Customer wanted to run pump gas at about 16-18 psi.

Pastor · Oct 29, 2009

This is probably too simple but did you try adding more fuel at idle? At 17.1 A/F mine would not idle either.

IronHide · Oct 29, 2009

What does tps read??

Just a guess to go into diagnosis and check those numbers??

Good luck

RX-1MT · Oct 29, 2009

When I pulled it apart to remove the head shim I checked the timing and I was a tooth off that explains alot, we still opted to remove the shim and just go with the low comp pistons! I guess instead of double check I will triple triple check timing, got in a hurry I guess to get it done. Oh well we all like to do things twice right!

:beer;
Thanks to all for your help!!

Apex won't Idle

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