Thread: Gp1200 lasted 10 hours
11-03-2013, 04:15 PM #1
Gp1200 lasted 10 hours
Had a ball today, cold front came though last night so there were some decent waves for us gulf coast peeps. I noticed on the way out from the ramp that the motor acted like it was not running just right figured there was some air in the lines as we didn't go out last week so ski sat 2 weeks. Never got much wot as waves were 3-4+ out on the open water. On the way back in got wot for about 45secs and motor bogged and seized. Started back up and idled for about 20 secs and shut down. Towed it in from there. For some reason the security system locked me out reset the code at the house and it started..... Sounded pretty ruff. 100 on mag135cen 137 pto. Plugs say it ran lean on mag. Also some detonation is appearant on the piston.
Would an air leak somewhere cause lean condition on 1st hole? Moter has 12 hours since rebuild. Passed leak down at time of rebuild, and carbs were rebuilt by Jim. All fuel lines were blown out, tank and fuel selector were removed and cleaned. New fuel filter.
11-04-2013, 09:58 AM #2
Could be air leak, dirty carbs ( again), bad fuel select valve, Poor quality fuel, etc. I have found just "cleaning" the fuel select is not good enough, I eliminate, or replace with new.
Do a leak down test on the motor BEFORE you disassemble.
11-04-2013, 06:41 PM #3
Brett at Jettrendz has it for tear down. He does my boring anyway, he is going to tear it down step by step and determine what the failure was for me. Figured since I think I did everything right and it only lasted a few hours I will let someone that does it all the time tell me what went wrong instead of me guessing at it.
11-11-2013, 06:59 PM #4
Up and running again turned out to be a carb issue...... Creased something or another and something else and carb was not delivering fuel properly. They were very clean tho. Note to everyone. Make sure your carbs get rebuilt with genuine parts not after market kits.
11-12-2013, 10:59 PM #5
Creased check valves are a common problem on the GP's. Have you done the balanced return mod? It will happen again if not.
11-13-2013, 08:14 AM #6
Getting ready to. The jets just got here yesterday. Going to do it on both machines.
11-13-2013, 08:25 AM #7
My wife doesn't know it but I'm going to take another .010 off her GP's head to get compression to about 145 then do some rejetting and find an aftermarket f/a setup. I'm going to mod the fuel pickup and put clunks in all my machines also.
11-13-2013, 06:04 PM #8
Clunk? That all sound awsome other than me not knowing what "clunks" are.
I am nervous to do too much to mine as far as the carbs go. I wanted to remove choke plates, add after market flame arresters and then of corse reject for all this. However I pretty much dog the hell out of these ski, I got it for the purpose of wave jumping. Even submarine it from time to time. The amount of water I get in the hull is ridiculous. The stock siphon does a good job of getting it out but when I am getting good air and landing tail first I have noticed the motor gets splashed some. Took the seat off after a 1/2 hour of jumping and noticed this. I think stock box is safest for what I am doing with mine.
As far as the drilled return goes do I need to adjust the carbs leaving everything else stock?
11-13-2013, 09:53 PM #9
Clunks are little weighted pickups that go on the ends of the fuel lines inside the tank. It keeps your fuel pickup on the bottom in the fuel instead of mixing with air when everything is sloshing around.
Carbs should be upgraded to known good jetting specs. Cutlass on here will have all the info you need.
11-13-2013, 10:11 PM #10
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
By pilo704 in forum Yamaha ClassifiedsReplies: 17Last Post: 07-31-2009, 09:52 AM
By scottbaty in forum Yamaha ClassifiedsReplies: 8Last Post: 03-20-2009, 09:38 AM
By NCRXP in forum Yamaha 2 Stroke SkisReplies: 4Last Post: 08-23-2008, 10:51 PM
By MIARider in forum 4-Tec PerformanceReplies: 13Last Post: 01-10-2008, 11:03 AM
By Hydrotoys in forum Yamaha How To & FAQsReplies: 6Last Post: 02-06-2006, 03:31 PM