blowit

Are you running outerwears? If so, pull them and go try it. Seen it in the shop too many times. They are crap! B

No, but you might try jetting and timing changes to see if the problems will tune out. Actually too much timing will reduce top end performance so you may try bring it back a bit but I suspect the porting is not working with you. You must always rejet when you report. If you have not, there might be an issue right there. Look at your plugs and let them tell you what it needs. B

I am really thinking this thing has a dispersive flow pattern and is not scavenging right. There really is no way to make a transfer round while maintaining proper port flow. Velocity is key. B

I would be real interested in seeing some pics of this port work! An oval port window for the transfers is not ideal unless the entire port tract matches. If you want to send them over, hell, I would inspect them and mic them free of charge just to see this.. It is possible that we can correct them but sounds like they might be hogged too much to be helped. How did they run on a normal ride? Pipey, no power anywhere, etc? B

We are playing around with a few things in the shop and cannot find ANY stock impellers when we need one. Looking for a stocker, still on the shaft, and also the drive gear. Would like to find with some old bearings as well. Bearings do not need to be any good. B

:thumbsup: X2 Had to have knocked the crank out of phase. Good idea to check that thing out for sure... That ain't no .030" of squish. We have run motors as tight as .020 without any contact problems. The rod will NOT stretch that much so that just leaves bearings and pistons. Sloppy tolerances and fits will certainly cause this. I will admit, I have NEVER seen one that bad!! Can I have one of the pistons for educational purposes. :geek: B

Depending on mods and tuning, you should be fine with it. Keep in mind that set timing and "actual" timing are never in agreement. What I mean is pick up gap and other factors and tolerances will dictate how much advance you "really" get. ie, +10 may work great but may only be giving you +7 actual degrees of advance. I would recommend to start at +6 and go up +1 with a plug check at every interval. Will know when you hit the wall. READ CLOSELY, when the bike pulls hard but fails to pull way up top like it just cannot quite get there, you are there, back it off!!! Pushing this wall will hurt the engine. It is best to monitor EGT when doing this because as noted, you will increase your combustion chamber temps and decrease the pipe temp. I would guess that you will find the "happy spot" around +8. We have done extensive research in timing and head design and I will say that if you have to push to +10, you probably need head work to increase the volatility of the mixture. way advanced timing does nothing but heat up the mixture at the cost of negative engine work. The closer to zero degrees timing you can run to get max power, the more efficient your engine is. To put it dumbly, increase compression and turbulence rather than bumping timing. B

That is a smart and GOOD question. I have had many instances where a customer brings us a new bike that will not run right where the previous owner ran Meth and the new owner thought E85 was alky! Um, even 100% Ethanol will be WAY off. Good thing to check. B

Why don't you check the actual displacement of the dome? The down and dirty method is to use a syringe instead of a burette. Some here can walk you through the procedure. Best to see what you have.... B

x2 on syncing the carbs. this is an adjustment at the top of the carbs that balances the slide motion so they open and close as the same time and rate. The eye ball test will get you close. Many times you can clearly see the problem. Plenty of threads on this on the forum. Just try the search feature. B

You will have a hard time finding a shop that can truly check the rods for straightness without just giving the o'l eyeball test. Every time I have have seen a hydrolocked motor, it is VERY obvious things went wrong. I suspect the rods are not bent but my official answer is "sent the crank to a crank specialist". B

Just keep in mind that those seals rarely fail due to wear because they run in oil on both sides. Many times the crank develops radial play in the bearings or the PTO bearing frags and chews up the seal. I have seen many PTO bearings keep right on going even with the cages and maybe a ball or two missing. Smart ears will hear the "ball slapping" pretty easily. I lost track of how many engines I have seen with bearing noise down stairs. B

Get a new plug and squash it slightly in a vise to expand the OD slightly so you increase the interference fit. Also a good idea to apply a small amount of RTV to the OD to help seal it. Should be a 5 min job. B

Not throwing opinion one way or another but just FYI a steel gasket will out perform an o-ring hands down, any day of the week. O-rings have their place and work on the Banshee but to say they are better than a gasket is a bit misleading. B

You are on the right track. :thumbsup: If you grab a new PTO side seal, you will see the little rib, if you are an experienced tech, you will know what to do... Yes, the seal will be fine just pressing it in and you are right, most engines use a press in seal anyway. Yamaha simply added the rib because they could due to design, that is it. The only situation where I had one come out was a turbo bike so that does not count. It WILL work.. Brandon

Yes, it should be repairable. Yes, you are correct on the phasing and it is something most shops will not check because it requires more tooling and time to do so. Lost track of how many cranks are out there that are out of phase. Probably can take it to a competent crank shop for truing and welding or send it to someone like Falicon or Crankworks. B

The rib down the center of the seal is not a design necessity, but rather an opportunity by design to ensure fitment. Most engines have been using press in type seals for decades without problems. I have never had an issue doing it this way but I will admit that since that seal rides in oil, unless there is obvious damage to the seal, you have have other issues like radial play in the crank bearings. Just a thought... B

I have had to do it in a race situation before. Will need to cut the bead off the outside of the seal so it will go in. Use some yamahabond around the OD to help glue it in place a bit. Done it several times and never had an issue. B

It might be worth going over all the aspects of the engine now along with your riding preferences. It sounds like an aggressive dune port is still an option but measurements and pics are a must at the least. If you want me to look at them and possibly fix, I may be able to squeeze you in over here. A guy will just have to see the things in person to know where to go with them. B

I thought I recommended against doing just this?? :confused: Let me guess, a light switch??? I would recommend getting the cylinders to a porting guy to see if they can be saved. Where are you on the transfers and booster (purge port)? At the risk of sounding like an ass, I will say if you do not know what you did, it will be difficult to tell you how to fix and even at that, I think it is time to visit an experienced tuner. Do this BEFORE you ruin them unless of course they are toast anyway and you are in the learning phase.. If that is the case, get the tools to work the transfers. I am confident you have too much offset between your primary and secondary transfers. B

I would recommend you start with a call to some engine builders. For one thing, I am nearly positive your 280 main with OOFs is too small. Running OOFs just for a look will hurt you in the performance department. You will need radical port timing to take advantage of them. I too would recommend going to an in frame pipe. You are no where near needing OOFs yet. Put it this way, that bike will straight way UP when you put the right pipes back on it. T-5s have always been a good choice for no port to wild port engines. B

Sent a PM days ago indicating I would take the head. Let me know. B

Just taking a stab at it, the CR may be a bit high even at 6K ft. The 410 is an odd size unless it is a 7mm motor. Never the less, if the CR is as high as I am envisioning, things will have to be setup right. We have set up a few 18:1ish motors but they need special care and are not for drag racing! B

There may be a few things that are going on but a rich condition will burn slower and a slower burn is not desirable because it will tend to transfer heat into the engine more than a fast burn. That being said, in a rich mixture, there is usually partial fuel that is not burned and helps to cool things. Hard to say without knowing more but I can tell you I have seen it on the dyno but that was a full load condition. Maybe once it burns down, we can get to the bottom of it..... B

Well, I would not say we have all the answers. Just not enough hours in a day I guess. We have learned some unique differences in chamber designs relative to plug gap, heat range, spark kernel distance from piston, etc. That all plays in. You will also notice we do some squish work with our heads. It is our engineering goal to push the limits of MSV and heat because that ultimately drives the efficiency of an engine. An overall reduction in spark timing is what we are after because advanced timing is negative work done. We have been able to take timing well beyond what is typical and still get performance improvements. That just means there is a lot to be desired in the CC. Just monitoring AFR and EGT are very interesting with CC and timing work. MSV also has drastically different effects depending on fuels. Even for pump fuels, state of origin, and time of year purchased. ie, what additives are in the pump fuel. In a nut shell and to be honest, it is bothersome that we can only get 50% efficiency from the chemical to mechanical conversion of gasolines. We are always trying to find a way to increase efficiency. In a perfect world, efficiency and power should always go hand in hand. B