juan_carlos__007 Posted June 2, 2015 Report Share Posted June 2, 2015 Don't know where to begin, but to make a long story short I'm new to banshees which are highly modifiable and need your guys' advice. I have a a banshee which I bought from a guy who said it was a long rod 370 with blaster pistons. I have done some research and I am overwhelmed with all the info, like spacers under and top cylinders or porting for timing, also either to go with longer rods or longer crankshaft which both affect angle for timing etc. I checked the compression with a tool loan service from autozone it was in good shape, but it read 80 psi at wide open throttle, and forty kicks with both spark plugs removed. Banshee runs but I'm noticing a lot of bogging and yes tors is removed along with e brake cables, and also have cleaned the carburetors which had a 340 or 370 main jet I don't remember clearly also have plaid with needles going up and down many times. So I wanna just fix the issue and restore power on a budget, not go big with custom cylinder or anything like that. If what the old owner said is true and the pistons are blaster 66.00 bore and cylinders, What I've been thinking in doing is the following options: 1. Check cylinders for imperfections such as scrapes, and uneven 66.00 bore top to bottom, also check piston rings for correct gaping and if it's just the rings replace them, and put everything back together. 2. If cylinders need to be bored 66.25 can I just install blaster pistons that size with new rings and get away with it? Cause I believe in my research I've read something about longer rods affect timing and wont work with banshee pistons and also different domes installed on the head which I' believe is stock since it has a yamaha symbol on top, but with modified domes? 3. Use same pistons with new rings, with cylinders 65.50 ready to be bored to 66.00 from someone selling in the bansheehq community I have run out of ideas for the budget build, as always thanks for the good talk in here. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted June 2, 2015 Report Share Posted June 2, 2015 66mm is pretty much the standard in max bore for the stock cyls. There's a few fellas with them at 66.25-66.50mm, but make sure the tune is spot on or it won't live. If you can get away with a hone go that route with fresh pistons and rings. Maybe rings if your pistons truely are in good shape. With that bore and a long rod crank you should definitely be using the Blaster pistons, but make sure the head/domes are set up for it as the blaster piston has a different shape crown. As far as tune up, a 340 is a lot of fuel for stockers! Are they ported? If not, that will be a different issue. Give every detail on the motor set up and guys can help steer you toward the right jetting. 1 Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted June 2, 2015 Report Share Posted June 2, 2015 first thing I would do is try a different tester, if nothing more than to double check comp. Measure cyls and pistons for wear and clearance. That will be a big factor. Before you tear it apart do a leak test, as the large jetting may be masking a air leak. You'd hate to get it together andthen find a leak and have to tear it back down. Quote Link to comment Share on other sites More sharing options...
n2otoofast4u Posted June 2, 2015 Report Share Posted June 2, 2015 Remove motor Send to builder Install motor upon return from builder Enjoy Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted June 2, 2015 Report Share Posted June 2, 2015 Lol green is rite no offense your not set up to determine if it's good or not a 370 is a hot set up I've built a few. I highly doubt it's not ported and I've done a few that were sleeved with big sleeve kits to occomodate future bores. To me I wouldn't build that caliber of motor and not port it Quote Link to comment Share on other sites More sharing options...
sheerider11 Posted June 2, 2015 Report Share Posted June 2, 2015 Lol green is rite no offense your not set up to determine if it's good or not a 370 is a hot set up I've built a few. I highly doubt it's not ported and I've done a few that were sleeved with big sleeve kits to occomodate future bores. To me I wouldn't build that caliber of motor and not port itRudy. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted June 2, 2015 Report Share Posted June 2, 2015 Rudy.I've got to swing a leg over one of those Rudy Kurtz 370's. Pretty boss! Quote Link to comment Share on other sites More sharing options...
juan_carlos__007 Posted June 2, 2015 Author Report Share Posted June 2, 2015 I feel confident at taking the motor apart, I've done two car engines and they have been running for years now one is my 99 grand cherokee daily driver, but followed manuals step by step. I wanna tackle this project myself as if everything goes good I learn a new thing and if it goes wrong well I can learn from my mistakes. The guy never told me anything about being ported. So even if it was a bad long rod 370 it shouldn't be 80 psi on the compression? I guess I'm gonna buy a tester since is a pretty good way to check future engines and give it a second try. Leak test I'll have to read more on how to do that but still low compression is my primary worry. I think the old owner told me something about that engine having more lives left in it with sleeves. Guess gotta start getting my hands dirty with this engine and get to know whats really inside and read a bit more of thatrudy kurtz build Quote Link to comment Share on other sites More sharing options...
bigweav81 Posted June 2, 2015 Report Share Posted June 2, 2015 You should do a leak down test before tearing it down! sent from yo mammy house Quote Link to comment Share on other sites More sharing options...
juan_carlos__007 Posted July 3, 2015 Author Report Share Posted July 3, 2015 (edited) Ok took long, but I did a leak down test and found leaks in between the cylinders on the bottom. upon disassemble found out in fact it had blaster 66 pistons and the cylinders were bored and ported. To make the long story short I rebuild the top end with new wiseco 66 blaster rings, new gaskets, and silicone since the port job was too close to the edge where they were leaking. Now it has power, lots of power but until it hits the power band really high. Is this due because of the porting done or jetting on carbs? In example going up a hill it does not have power I can kind of hear the engine detonating without power until the power band is reach then it wants to tear the hill off. Tomorrow I will do another leakdown test. Edited July 3, 2015 by juan_carlos__007 Quote Link to comment Share on other sites More sharing options...
Strm Trpr Posted July 3, 2015 Report Share Posted July 3, 2015 Need to know your complete mod list. Carbs <-- list all jets Intake Reed Cages Air Filter Pipes Elevation Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted July 3, 2015 Report Share Posted July 3, 2015 Did it pass s leakdown after rebuild 6 lbs for 6 min, as said list of all mods, what's your compression at now Quote Link to comment Share on other sites More sharing options...
Coupelx Posted July 3, 2015 Report Share Posted July 3, 2015 silicone on base gaskets is a no no. Quote Link to comment Share on other sites More sharing options...
camatv Posted July 3, 2015 Report Share Posted July 3, 2015 cometic afm style should seal fine with no sealer.. you can use sealer ( yamabond, ultra grey ) on any gasket surface. just not on paper only type gaskets. i have lots of problems lately with intake gaskets leaking with stock boots. i just ultra grey them right up. no gasket at all works great. Quote Link to comment Share on other sites More sharing options...
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