Polaris virage tx timing issues

[Rayman1975]

I know this subject has been covered before on here but I still can't figure out whats going on. Bought a broke down ski and went through the whole thing, rebuilt engine, carbs and pump. Starts great and idles ok but won't rev up, if I get it to rev up it will start backfiring out the ehaust. I have the flame arrester off to watch gas flow while running and when hitting the throttle and that seems normal So it seems to me to be timing issue. I did the dial indicator thing and rolled it over to top dead center then down about 5 thousands and made a mark, looks like it is .250 from the zero mark on the flywheel, atdc. I made a mark also on the 23 degree mark on the flywheel then ran it. Can't seem to get any marks to show up with my timing light. My light has advance on it and even with engine reved up and with my timing light set at 23 degrees no marks show up in window?
I have a hard time keeping it around 3000 as it is running terrible but I feel I should be able to see one of the marks at some point. I am stumped and could use some advice in regards to checking timing. I sent my engine to have bottom end rebuilt so they dropped in another crank, could that be the issue? Flywheel and stator when back in normal, key is in flywheel. Anyone have easy to follow ways to check timing? Thanks for any help. 2002 virage tx 1200 carb

[casey67]

I would like to clarify a couple things.

With front cylinder ( AKA MAG, #1, Cylinder furthest forward towards front of PWC) at TDC, you could see the 0 deg timing mark at center of timing hole ?

If you are marking flywheel, it needs to be BTDC (before top dead center) that is when spark occurs. The timing scale is BTDC.

You are using the #1 cyl, furthest forward, for the timing light.

[Rayman1975]

Yes I am, cylinder in the front. I will check TDC again and verify if 0 is more lined up in the window. I could have made a mistake with the dial indicator. From what I read at 3000 rpm it should be at 23 degrees BTDC. So I figured with the timing light going and the engine running at 3000 the 23 degree BTDC mark should show up in the window, and it doesn't seem to be. I was able to get to the lake and with a bunch of tinkering I got it to go. Bogs and dies below 3500 rpm but once it gets past that point it screams. Pulls hard and fast. So not sure if it's timing because of how well it runs on the top end. I do know something is wrong with the slow speed mixture.

[casey67]

Most timing lights are geared towards 4 stroke engines. That fire the sparkplug 1 time for every 2 rotations of the cranshaft.

2 stroke engines fire the spark plug every rotation of crankshaft. So twice as often as a 4 stroke. The degree setting is going to be some sort of timed increase. Don't use that. Just leave it at zero and use the flywheel scale.

The only 2 stroke timing light I have seen was an OTC model that had a switch for 2-4 stroke.

The #1 piston is directly connected to the crankshaft snout - flywheel key way. If flywheel does not align to zero, it is installed wrong.

[casey67]

Back firing troubles me. Plug wire could get miked up.

With electrical box mounted to the bulkhead.
Looking from rear of ski, the plug wires should be 1-3-2 from left to right

[Rayman1975]

Thanks for the advice and imput. My timing light has a button to switch from 2 cycle to 4 cycle so have that covered. Flywheel definitely keyed into crank and tourqued to spec. It's been so hot out I haven't played around with it much. I did check the idle mixture screws and made sure they are where they should be, oil lines pumping as they should, compression 137 all the way across. I will double check plug wires when I get home. I rebuild 2 stroke dirt bikes so that style engine not new to me, just the whole pwc thing is. Still leaning toward low speed fueling issue. Read that air leak in fuel shut off valve or system can cause a lean condition? Have any knowledge in that area? Also I rebuilt the carbs as they were full of garbage and rust. Got a cheap rebuild kit but I didn't like how the fuel bowl diagram looked on the new kit so I put the oem ones back it. Verified needle valve arm depth setting. I took my time and think the carbs in tip top shape. I am still running 50/1 in gas tank until break in is over. Hope to get it back to late and see if the low rpm issues are there or not and will post my findings. Thanks Casey67

[casey67]

Need to make sure of the timing. Being exactly 3000rpm isnt critical,most idle around 24-2600 out of the water, timing won't change from there to 3000.

Did you check the "pop off" pressure ? Seems alot of rebuild kits springs don't match factory spec. Pretty sure thats the most critical for low speed.

Using a peice of clear fuel line will help see if air bubbles are present (leaks upstream of pumps). Air bubbles would proably lower the fuel pressure-wreck high speed more.

Is accel pump working ? (small brass tube at top of each carb throat) The accell pump does hide some evils in low speed.

[Rayman1975]

Like the clear hose idea, I replaced all the hose with new because of the green goo issue anyway so I'll cut in a piece of clear and check. The acc pump does work with good squirt into all carbs. I did reuse oem needle spring as kit came with some but none really matched up. I didn't check pop off. Thought that with new needle seat orings and new needles and oem springs there wasn't much of a chance of leakage. Maybe I was wrong? I will also go back and try and get timing figured out. Probably leave it straped to trailer so I can run it in the lake without being In a hurry. Should be able to make that happen here soon.