shawn_NJ
Chasing waves.
- Location
- Daytona Beach
Does it look like this one? ie no bottom screw.
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750 big pin seizure !!!!
- Thread starter x2fatkid
- Start date
- Location
- antioch ca
Yes it looks just like that! I'm not sure the diameter,i'll have to check it next time i have it off.I'm going to take the ski to a shop today that jetted my ski last year with great success,we will see if they can make this set up work just as well.I have not worked since dec so money is tight but they are pretty sure they can get it right in about an hours labor..If that is the case then it is well worth the 106.00 per hr.I just want to ride my ski ..already had a taste of the power again compared to a 650,i know why i wanted a 750/800 motor.
shawn_NJ
Chasing waves.
- Location
- Daytona Beach
Pull that headpipe/ex manifold and check the diameter before you run it! That oldschool 650 headpipe is a POS, trust me I had one. If its too small odds are your just going to cook another topend. Save the $$$ you are going to give hte shop and get yourself a 46sbn. Jet it as I posted and you'll be really happy. If the shop isnt actually going to ride it the tuning will be subpar anyway.
Where is your 650 timing set to?
Where is your 650 timing set to?
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- Location
- antioch ca
Ok just put a 46 sbn with you're jetting specks 2.3 n/s 120L 150H on will water test maybe Thu/fri .What should i set the fuel screws at?Do you think some of the piston problems are related to the blaster chamber?And the head pipe and manifold have been opened up not sure of the diameter..
shawn_NJ
Chasing waves.
- Location
- Daytona Beach
Cool! Bunch of guys are running the blaster chamber so that shouldnt be an issue. Do you know where your 650 timing is? You are still going to have to tune the screws. You can tune the low speed on a submerged trailer with the ski strapped down. Groupk has a great write up for this and its not hard to get that close to dialed in. For the high speed, turn it 2 out and check the plugs after a 15-20sec WOT chop. Do what the plugs tell you if you dont have a tach. I believe my coffman pipe ski is 3/4 out on the high, and my FP SJ chamber ski is 1Turn out, or something right around there.
- Location
- antioch ca
Not sure of the timing but was told it is very minimal.Thanks for you're help i'll try those settings my self..
- Location
- antioch ca
Do you have to bore the head pipe and the manifold?The manifold is a stock TS mani opened up not sure of the size...Ran the ski twice now once with a2.3n/s 120L 150H with the blaster chamber,ran pretty crappy i think it was to rich on the bottom,might of fouled the pluggs.messed with the screws a bunch but i think my pluggs were shot.So i decided to change a few things,pulled the intake mani and reeds.resealed and replaced the reeds,not sure anything was wrong with the reeds but the petals don't seal on the reed blocks.Had another set of FMF torq reeds so i just changed them..also decided to go back to the 650 chamber,and a new set of pluggs just to see if that would help. Ran the ski again Sat not much better ,still boggs on the bottom..closed the bottom screw to 1/2 turn seemed to get better!So i put a 110 L and a 155Hput it back together gave it another try..little betterstill not right..also opened my water screws up the pipe, was very hot sizzeled all down the chamber and tailcone.2 turns on top and bottom,still hot!The ski runs great from mid to full throttle boggs on the low .I think that my gas tank is not pressurizing,would that have an affect on the low end only?And i am going back to the blaster chamber, hits harder and it seems to run cooler..still rode all day just not much lowend.I think i will try a different fuel pickup and seal, if i can find one.I think i'am close just not that great at carb tuning!
- Location
- antioch ca
bump
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- Location
- Amherst NH
The tank does not preasureize.
shawn_NJ
Chasing waves.
- Location
- Daytona Beach
When your troubleshooting you should not go "change a few things". Just going to make it much harder to isolate the problem. I'm confused...Are you saying that before (or now) the reeds are not sealing against the blocks? That will make it run like complete ass (if at all). Start there. Make 100% sure the reeds ARE sealing PERFECTLY against the blocks. I would also recommend putting the jetting back to where I told you and retry.
BIG PIN motors do not have great bottomend, but it still should run pretty good if setup correctly. Looks at this reed picture, this tiny problem caused my skis to run with HORRIBLE lowend. Messed with the carb for a few weeks before I broke down and checked the reeds. Swapped them with another set of stockers and instantly fixed.
- Location
- antioch ca
Yes the reeds that i had in there before did not seal so i replaced them.most of the petals looked like the bad one in you're pic..I did run the ski with you're jetting after i changed the reeds and it still was not right,it ran alittle better with the bottom screw almost all the way in ,so i lowered the pilot jet and it helped a little,i also went up on the main.It's loading up on the lowend.i'm checking my tank and pickup today or wed.When your troubleshooting you should not go "change a few things". Just going to make it much harder to isolate the problem. I'm confused...Are you saying that before (or now) the reeds are not sealing against the blocks? That will make it run like complete ass (if at all). Start there. Make 100% sure the reeds ARE sealing PERFECTLY against the blocks. I would also recommend putting the jetting back to where I told you and retry.
BIG PIN motors do not have great bottomend, but it still should run pretty good if setup correctly. Looks at this reed picture, this tiny problem caused my skis to run with HORRIBLE lowend. Messed with the carb for a few weeks before I broke down and checked the reeds. Swapped them with another set of stockers and instantly fixed.
- Location
- antioch ca
Well i took the ski to the ski clinic in antioch for performance tuning.But before i did that i had the head pipe and manifold match bored to 47mm.Took it out last sat ran alittle better but not much...they replaced the butterfly and throttle assembly,because the week before a e-clip fell off and messed it up.They set the jetting at 155H 120L 2.3 95gram spring 1turn out top and bottom screw.The ski still boggs and falls on it's face when i turn hard right,and when i take off from shore it takes atleast 3-5 seconds to clearout and get up to plane! So on monday i took it back to them and they water tested it again,the owner derrick actualy rode the ski for about 15min and confirmed that the jetting was fine but it still falls on it's face when you turn hard right,and it stil loads up when taking off from shore.He thinks that there is to buch water in the exhaust,suggested that i try closing the bottom screw and opening the top screw only a half turn.Tryed that yesterday and that did not help much.Going to try and open the bottom a half turn and close thetop screw se if that helps ...keep in mind that i have an old head pipe that only has 2 screws,top and middle but i call it the bottom screw.the next test would be to swap the head pipe for a freinds head pipe thats newer but still only has 2 screws.If that works then i will check my head pipe for internal leaks.Will the pipe run too hot with all th screws closed?
shawn_NJ
Chasing waves.
- Location
- Daytona Beach
Is the carb holding 20ish psi on the popoff? Have you eliminated all extra fuel system BS (bypass on/off/res switch). 1 line strait from RES fitting on the tank to the carb IN, and 1 from the return on the carb back to the tank? I had a leaking primer that was letting air into the system. It would make it almost impossible to start if you fell off and it would stumble getting going.
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madscientist
chilling with these guys.
- Location
- good old p'cola
if the primer line is run to the old oil inj, fitting it will draw extra fuel in at different rpms through the primer. also run the primer on the return line side of the fuel lines so by pumping it you are also priming the carb internals. . the ouput side of the primer needs to be above the butterfly to eliminate the carb vacume from drawing from it.
this could be your culprit
this could be your culprit
- Location
- antioch ca
Not sure of the popoff ,but i have lost all the extra fuel selector bull 
.Jetting is set at 155H 120L 2.3 95 gram spring,should be about 20psi..On another note how much air do you need coming in to the engine compartment? My air intake has been filled and i have a 2" opening in the back of the hood hump..
DSC00071
.Jetting is set at 155H 120L 2.3 95 gram spring,should be about 20psi..On another note how much air do you need coming in to the engine compartment? My air intake has been filled and i have a 2" opening in the back of the hood hump..DSC00071
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- Location
- antioch ca
Not sure of the popoff ,but i have lost all the extra fuel selector bull
DSC00071
[/QUOTE My KTM 450 runs way better than my X2! Well its that time again,the motor is back up and running after i blew it up again...New pistons rings and back down to a 750 small pin cylinder,still not right i'm going to pull the cylinder off and have the clearances checked! he says he put it at 40 -45 thousands. I think that is to tight..What do you think?