Jetmaniac 735 Carb Question

[xixp]

Hi Blue, a related question..
I have a JM 760 top end kit and since i got rid of the choke plates i have a slight low speed hesitation . (I have 75/137.5 jets with stock FA ).
What should be the pop off value i should use? (I understand i should lower it but how much?)
I tried playing with the low speed screws without luck so i guess the pop off is the issue.

Thanks!


Sent from my iPhone using Tapatalk

 

[Blue]

Yes it could be. Stock is around 55 psi with the gold spring. With the silver spring you should be in the 40 to 44 psi area. Most times there spot on at 42 psi when i check them. Test your carbs and make sure everything is good and there not leaking when you pump them up. They should hold the pressure as you slowly pump up to the popoff psi. If they dont fix that issue and see where they pop. Good luck.

Sent from my SM-N950U using Tapatalk

 

[xixp]

Thanks for the input Blue, im in the middle 40’s (i cut the stock springs because i didn’t have at hand gold springs).
i will replace the springs then because i wasn’t good at cutting stock springs (i had many for previous rebuilds) so it was hard to get both at a similar pressure.



Sent from my iPhone using Tapatalk

 

[Blue]

Gold is the stock color which pops at 55. You will want the silver there closer to 40ish. Jetmaniac has them.

Sent from my SM-N950U using Tapatalk

 

[JetManiac]

Thanks for the input Blue, im in the middle 40’s (i cut the stock springs because i didn’t have at hand gold springs).
i will replace the springs then because i wasn’t good at cutting stock springs (i had many for previous rebuilds) so it was hard to get both at a similar pressure.

95g is what you want.

 

[Ryder]

Hey guys, I know this is an old thread. But I’ve got a brand new, old stock, ported 735 top end kit, purchased from Jet maniac.

I’m in alberta Canada, 3100 feet above sea level.
And wondering what I should be at for baseline jetting/ carb setting.

I’ve got the option to run 35cc or 38cc domes (I have both on hand)
B-pipe mod
Jetinetic’s lightened flywheel going in
MSD enhancer
Stock 38 mikuni’s (jetted years ago for B-pipe)
Carbon tech reeds (stock intake cleaned up)
TDR water box


Any guidance would greatly be appreciated!
I’m rebuilding the entire motor and installing this top end.
I will also be rebuilding my carbs, removing the choke butterfly’s, and installing T handle’s as well as adding a primer setup.

 

[Dorny119]

You and I have very similar builds. I am nearly at sea level, so keep that in mind. I have 35cc domes. You should run those. Here are my carb specs. My ski runs great at full throttle for any period of time, and hits off the bottom very well. The only issue, is maybe a little rich for starting when it's hot. For your altitude, you will probably need to reduce each of these settings proportionally (except NS). I am not sure how much.

Low Screw: 1 out
High Screw: 2 out
NS: 1.5
Low Jet: 75
High Jet: 140
Pop Off: 26psi

 

[Ryder]

You and I have very similar builds. I am nearly at sea level, so keep that in mind. I have 35cc domes. You should run those. Here are my carb specs. My ski runs great at full throttle for any period of time, and hits off the bottom very well. The only issue, is maybe a little rich for starting when it's hot. For your altitude, you will probably need to reduce each of these settings proportionally (except NS). I am not sure how much.

Low Screw: 1 out
High Screw: 2 out
NS: 1.5
Low Jet: 75
High Jet: 140
Pop Off: 26psi

Right on, thanks for the reply!

It’s a set of 34cc domes and 35cc’s I’ve got.

And a custom .030” base gasket.
I shot chris a message, see what he thinks about that setup.

 

[fastgtfairlane]

A riding friend has a jm 718 or 735 in a tigercraft v3 with same bolt ons with a 155 oem pump with a 6/12 skat and 90mm nozzle I believe, he's at 80 pilot with stock flame arrestor, 1 screen, no chokes 95g spring. Might be worth trying a 80 pilot if you're having an off idle hesitation. Leave the popoff alone and try a larger pilot jet just to see if it's better. Not every engine will have the same carb tune. He had the same engine in a fx1 that had a Solas 144 mag with 9/15 hooker.. he had to retune the carbs after swapping hulls with the larger pump..

 

[Ryder]

Makes 100% sense.
Thanks

 

[TheBuzzard]

I've had to put I think 80s or 85s in there to lose the lean bog when you Crack it wide open from very low speed or idle. That's how you adjust the pilot jet. If you turn the low screw out 3 turns and it runs good. You need to go up a couple jet sizes to get the screw back down to 1 turn or so.