salmon_slayer06

Porting alone is not cheap but big difference. Put in some wisecos and a noss coolhead with 93 octane domes. Mod the stator plate to advance timing. Jetting will be critical now with more airflow. I like keihn carbs as there's nothing to them. You are just getting started. 1500 is nothing. That's new decent Elka skocks. Going to replace axle bearings soon. Its not too bad. I used the axle wrenches that you will find on eBay and a couple of 10 foot fence posts to help break those axle nuts loose.... Use a little heat and pb blaster

JDS makes one if anyone is looking...... http://www.jdscustoms.com/product/drag-cut-shortened-wire-harness/

old thread I know, but from what I can see in the manual they say the orange is towards the front of motor.... but I think that is wrong as there are + and - markings on stock coil. It is molded into it bewteen the spades on the coil itself. I'm currently diagnosing a no spark problem on a new serval build. Before build I had same problem and thought it was motor... Just spent 300 on a used good working coil, flywheel, CDI. And I have 2 good stators that show it being good according to ohm meter. I'm searching for a way to check pulse from CDI whick should be done with a 12V test light. Would like to pinpoint it before I swap out parts and possibly fry a CDI or Coil as these are getting harder and harder to come by.

thanks for the reply.

The front two stud holes are recessed and looks like its where you would install a dowel pin but the stock cylinders never had them. I'm setting the studs right now and will probably put the head on tomorrow. Its a NOSS cool head and these do not have the recessed dowel pin holes.... I'm guessing its okay but want to double check on here. Thanks-

Don't worry about asking questions. Thats what this site is for! Some questions might be answered by using the search function.

I loctite all the screws from last build. I forgot to heat the screw up and yeah. The other one was no problem. Thats what happens. Thanks for the info. I'll have to go get a new bit and tap for that. Hopefully center punching it and a good sharp bit will do the trick. Don't take much to bugger up aluminum.

I broke one of the screws off. Seeing it would be a pain to get the old one out I figure I could use just the one screw or just keep it off. I'm leaning towards keeping it off.

yes that is it, and thanks..

Its part number 15 in image. Its referred to as a cover. I broke one of the two screws off in the case and I want to leave it off instead of buggering up case. Anyone leave this off? http://www.macombpowersports.com/OEMpartfinder.htm#/Yamaha/BANSHEE_-_YFZ350W_-_1989/CRANKCASE/YFZ350W_%281989_ALL_TERRAIN_VEHICLE%29/CRANKCASE_%28YFZ350W_-_1989%29

low profile skat trak. Don't need a bunch of paddles maybe 8-10. I run these on a 400ex with a 440 motor in loose sand. Its fun to ride but tends to kick out a bit when turning and you can get sideways if you are on the gas hard. Its fun. I can't do this on the banshee because I have drag style skat traks on 8" rims and its more like balloon tires. Its woblles side to side on the trails... but the low profile I have on the 400 are much better. It does very good on the hills too. I plan on getting some new ones for the banshee once I finish installing a new motor. The one thing that I like about the skats is that they are light and are best traction in loose loamy trails and sand. If I were to pick another tire it would be the turf tamers. You can mod your tires by cutting the lugs off to form a type of paddle and this is what hill climbers do when in a certain class and can't run paddles.....

I would look at upgrading the suspension and making it wider. That will take a few thousand alone. Get shocks with low and high speed dampening. High speed are for those little irregularities on the trail. Not whoops but more like washboard. The old racetech/ TCS shocks were pretty good for the money back than. See if you can find the triple rates on Ebay and get them rebuilt.

When building a 421, do you replace the case studs with longer ones to hold the cylinders?

Do these need to be on there? What purpose do they serve?

Its possible the wire harness is grounding out on the frame somewhere, or you have a bad connection somewhere in the harness. I would also look at getting another CDI to try. I had spark when I had an electrical issue last time, and it ran...... but idled horribly and would stall out when given throttle. Bad CDI and my coil used at the time went bad. I had another coil already but the new CDI was the fix. I'm not sure why it went bad or why the coil went bad....... I think my harness was shorting out on the frame and wreaked havoc on the electrical. I recently pulled the harness off and found a spot where it looked like it may have been arcing to the frame. I'm still looking into it as I'm in the process of putting a 421 in.

IMO a properly oiled K&N with an outerwear prefilter is the best filter to use. I spary down the air box with a light mist as well as the intake to catch an fine dust. After a few weekends I'll wash the air box and prefilter and wipe the intake to see if its dirty. I'll never use foam

Does it do this when its cold or when its heated up, like after a long ride. Could also be that the carbs are out of synch. Could also go for a good ride and check the plugs out. Has your coolant level changed? Like others have said, you want to do a leak down test. You will be pressurizing the cylinders and spray some soap and water around the cylinder bases, carb boots, head gasket area, crank seal areas, for signs of air leak. Wad up some paper towels or a rag into the exhaust ports and the same for the intake boots. Use a air nozzle with a rubber tip on it under low pressure and soak down the area that were mentioned. Be careful not to over pressurize it you will blow the seals at the crank. Should notice a major leak right away. There is a trans breather tube at the rear of the motor on top, probably has a bunch of crud around it, if its bubbling here the right side crank seal is bad. So really pulling the stator cover off, removing flywheel, removing exhaust, take carbs off but leave the boots/ intake on. The correct way would be to go to harbor freight and buy an engine leak down test kit which are in the 30 dollar range or so, and get some rubber plugs or boots and hose clamps to fit over the exhaust and carb boots. Good luck.

Bad CDI. Fixed it. What a difference it made. My timing felt like it was off before the bike died. It gave me low end power like it was retarding the timing or something. My gut feeling was the key sheared and the flywheel was slipping. Still have my fingers crossed though.

Today I pulled the flywheel off and the key is not sheared. I swapped out the coil with working one and put new plugs in. Bike fired right up. After letting it idle for a minute it wanted to die if I gave it any gas or stalled when I let off the throttle. I pulled off the spark plug boots and checked spark with just the plug wire alone..... fat blue spark. I tried starting again and it backfired just like it did up north. Is this a bad CDI? I have V force 4 reeds and they are not more than a year old. Is this a reed problem. I HATE TAKING the carbs off to check.

double checked coil compared readings to a known good one and got the same. Checked the the stator again after I zeroed in the meter I was using to get more accurate readings. Checked out good. Traced wire harness no obvious wear through.... I double taped the entire harness when I rebuilt the motor couple years ago. Pulled off the stator cover, checked pick up gap.... in spec. Today I washed the banshee as it needed it. Tomorrow going to swap coils and check again. I read the electrical sticky, I'm leaning towards a bad CDI. Even if the flywheel sheared the flywheel key, I would still get spark. I have no spark. Any other pointers?

I'm not getting any spark. Checked the pick up coil. Going to double check the coil again.

Checked the stator used an ohmeter and everything checked out to spec. Checked ignition coil, checked out good. Checked for spark by using a spark plug and grounding it to the cylinder head while kicking over, got nothing. Bike backfires when you try to kick it over. Tried to start a couple times but idled, any throttle it dies. Tried again and couldn't get it to start. Checked continuity at main switch, checked good. Been down this road before but had to replace stator. Like mentioned not seeing any bad readings from this stator on here now. Was upnorth today, made it to M33 rose city trails from st helen and bike died. No warning signs, just dead. Luckily guy helped me, got a tow back. Can't catch a break with this machine. Pulled plugs, fouled pretty bad, put new ones in thinking might be problem and nothing. Just got back did basic tests using an ohmeter. Wanted to find problem and order parts and have fixed by next sunday. What I thought at first was stator went. Than possibly flywheel key sheared, or flywheel nut came loose. Didn't check that yet, will monday. Figure I get this in before I go to bed..... Any help is appreciated....

just ckecked both bars out. The flexx are cheaper, the 4 plays look to be better but are more and need an aftermarket stem from what I get out of it. This might be something I upgrade on the banshee. I only trail ride and put 100 miles or more in just 1 day. I feel it after a weekend of riding.

Keep the spark plugs in, loosen the stud nuts but leave on, kick motor over to help break the head gasket seal.....

Leave the case bolts in just loosen them up about 5 turns and hit these with a soft mallet in a criss cross pattern to break the case seal. I clean the crank and trans bearings with contact cleaner or something and reoil throughly with the trans oil or the 2 stroke oil for the crank bearings. I do the same for the connecting rod bearings also. I do this more for checking for binding or wear.