04-05-2011, 10:33 PM #1
Carbs and a good holeshot! Is it possible?
I'm trying to get my stock carbs setup properly and I'm having trouble getting the holeshot right, what can I do? Its a TJ ported 1300pv motor running a 14/22
I'm wishing I didn't remove my accelerator pump, think I binned it since From what I have read you need to feed the throttle on to keep the air velocity up to get a decent response from the carb without a pump. I have the low speed jet about one size up from where I would like it to be to overcome the lack of fuel from not having the accelerator pump. If I was to refit the pump I would go one size smaller on the low speed jet and the mixture would be bang on. But something tells me I'ts still not going to be what I'm looking for, even with a smaller prop it just dosnt like to launch from a standstill but mid range to top end is perfect.
I havn't drilled out the restrictors yet could this make a difference. I'm thinking of bitting the bullet and going NOVI
My friends gp1200 used to just want to get up and go with the slightest squeeze of the the throttle not sure what carbs it had but it definatley had higher compession.
04-06-2011, 07:01 AM #2
- Join Date
- Oct 2006
i run novi 48's and my hole shot is pretty good for a GPR with a HO pump and DF 14/23.
Speak to osidebill, he is the resident carb wizard around here and should be able to help
04-06-2011, 07:14 AM #3
You don't have to run 48 Novis to get a good hole shot. What is the jetting you are currently running? Is there a bog when you hit the throttle wide open from idle?
04-06-2011, 07:25 AM #4
04-06-2011, 07:27 AM #5
- Join Date
- Oct 2006
sorry i was not clear in my post, what i meant was yes it was possible and i had good holeshot with my setup as proof it was.
04-06-2011, 10:01 PM #6
Bill those are my specs and I set up the pop off pressure as per the manual for my n&s/spring combination. I found it to be slightly rich at idle some would think this to be ideal but I since tested with the lows turned in to 3/4 turn and it now runs a lot cleaner and has a heap load more pull. Its the transition from standing still to the plane that I feel its lacking.
I have since changed the high tension leads as I could hear a spark jumping when washing the ski down, hopefully this has something to do with the bad holeshot. I'm also yet to tune the top end as my tiny tach has been playing up Im hoping this is because of the HT leads shorting and all my problems will be solved the next time out.
04-06-2011, 10:46 PM #7
Thats why they call them adjuster screws every ported motor is slightly different some are thirstier then others. the right way to tune is do some hole shots and adjust lows and plug chops along with Tach to adjust the highs. Hole shot can be many things, including carb adjustments. Prop may be a bit steep water box has water in it make sure each detail is correct.
04-07-2011, 01:45 AM #8
Thirsty yes very thirsty
The waterbox? Iv installed the jetworks mod but it still feels as though my waterbox is staying full of water, are there any issues with the 1200r waterbox I should know about?
Is there a bog when you hit the throttle wide open from idle? (PolarisNut) - I wouldn't call it a bog as in it doesn't just die in the arse I can give it full throttle but it kind of just loads up and takes off slowly without picking up revs. Its quicker but definatly not quick if you slowly feed the throttle without loading the engine, it even did this with a 13/19 impellor.
I really hope the new leads make a difference I'll let you know this weekend.
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