You 100% sure you have the rotary valve timing correct?

ive checked it like 4x lol. Was going to check it again when i put the new carbs on but i forgot my degree wheel. and i was a half hour away from it.

I have the rotary valve from the stock 670x. i believe it is more extreme than the standard 670. could the carbs not agree with that rv?

How well does the ports on the manifold match the ports on the crank cases do they line up?

they didnt match, but i modified the seadoo intake so it now matches up near perfect. i didnt touch the cases as far as matching

Fuel delivery problem?
Vapor lock(or whatever they call it)when hot?

don't think it is a vapor lock, because it acts the same way cold, hot, or even after its only half warmed up.

I don't think it is fuel delivery either. Although now that you mention it, i have the fuel lines routed the same way hoser had said he had them setup(i belive) with the return line T'ing back into the main fuel line. I wonder if this has anything to do with it. Maybe it pushes an air pocket in there and causes it to starve for fuel? I was going to try taking that T out and routing the return line back to the top of the tank this weekend but i totally forgot about it.

My bad,thought it only acted up when hot.

no worries at all. im open to any and all suggestions at this point. If you told me to check the flux capacitor i would haha

wait wait wait explain this one please.......

your fuel line is ran how????

Your return lines should only return to the tank if you return them to your fuel inlet lines your pushing fuel into your carbs as well as sucking it in causing a super rich condition. Your probably dumping extra fuel in as you turn it off then pushing fuel in too fast when your trying to fire it flooding it out. Same result as to why it wont idle right. try running fuel just from the tank to the carbs and the return lines to only the tank. Are you using both pumps on both carbs or only one?

Ive got the twin carbs. The mag side carb is the only one with a pump. The fuel line runs from the tank, to the pump on the side of the mag side carb. the two carbs are connected with 2 short fuel lines exactly like they are on a seadoo.then the line that runs back to the tank, is plumed into a T in the line between the tank and the carbs. I believe hoser said he runs his this way, or i misunderstood what he said about his setup. Reason for this is because my tank doesnt have a return nipple. I will have to go and try removing the T and just running the line back in the filler of the tank and see if i can get it to start.

Yes I recirculate mine into a Tee about 5" from inlet side of carb any excess pressure would simply make a right turn at the Tee and flow backwards to the gas tank not over pressurize carb, WORKS FOR ME how ever after all you been through at this point I would dump the over flow into a clean water bottle and try starting and running it like shoubadaba suggested.

I would try playing with the fuel lines. Hoser is running 1 carb and it sounds like his set up works well for him but might be adding to your hard starting issue.

Now I have never setup a set of duals on an Engine before and looking at some pics online I see what you were talking about with how the fuel lines are ran on a pwc.

changed lines to where the return went to the top of the tank, and the fuel line went straight from tank to carbs. no change in the way it ran.

just took the intake off, double checked the RV. Its spot on. within 2* of where it should be. per the manual you have 5* of play.

Can the ignition timing be altered on this setup? It almost seems as though the ignition is off, and the carbs are not the issue.

Ignition timing on my Engine is completely adjustable fact is I can set the timing for each cylinder differently, I have two complete ignition systems on my Engine, 2 coils, 2 CDI (Capacitor Discharge Ignition) units, 2 triggers that are adjustable, most 2 and 3 cylinder sled engines you can only adjust both or all 3 cylinders to the same timing advance.

I have no idea what ignition setup your Engine has does it say anything in the manual about ignition timing ?

Well the ignition can be checked with a standard timing light. It is where it should be. don't know where to go from here other than ive got a nice paper weight.

I don't run a return gas line... One line from tank to pulse pump and two lines off of pump... One for each carb... I changed my carbs to accept the pump as they were set for gravity feed and it just never ran right with the gravity feed setup.. I run TM flat side carbs... I wonder if I should run a return line???
I wish you luck... The video I saw of the 670 looked very promising ..
Regards

He is running watercraft carbs they have there own Pump built into them

Then I as useless as my wife claims

My issue still lies as a lack of fuel when starting. With my choke carbs, i can close the choke and crank until my brushes in the starter burn off and it wont even as much as sputter or get any fuel. The only way i can get it to do anything is with the primer. It just does not make any sense.

Does the rotary valve being from the stock 670 have anything to do with it? Should i find one that went with the seadoo?

Well it seems to be starting better now. Raised the pop off to the weakest spring and biggest needle valve i had. Now im trying to get it tuned beter

I think its running rich down low. it wants to load up when it idles. Ive got the adjustment screws on the low side all the way in, so its time to go down a jet size i think? ive got 67.5s inthere, next step is a 65.

Good luck dude,wish I could help!

Everytime I open this thread I'm hoping to hear its running right.

I'M the same as Bull-Mike...Damn we feel ya pain/anguish Mate,SO efn close,bet it'll be something simple..

Not sure what the hell is wrong with this thing, so i am probably going to put it in the shed and forget about it. Just cant seem to win. Its running the best it ever has all through the entire RPM range EXCEPT it wont idle. It will either not idle. or it will not come down off of 3k RPM. plugs are lean. Richen it up, wont idle. turn idle screw to where it will idle, wont come back down after i rev it. Next time i should find something EFI. This winter i am going to keep my eye out for an Arctic Cat 700 or something.

Are the carbs too small or somthing? They are the 38 watercraft carbs so they should do just fine.