quadguy214 Posted July 22, 2005 Report Share Posted July 22, 2005 I've tried searching for threads on here about Banshee owners running the RD/RZ350 YPVS engine, but the search doesn't come up with much. I've had my shee for 18 months and it already had the YPVS engine fitted. Now I have much experience with this engine and know it inside out including the electronics etc, BUT i have always had a problem setting up the engine. It always starts well, runs well, pulls well, but the engine just doesn't last long enough, it will usually blow within 3 hours !!! I have tried hundereds of variations of jetting, but to no avail and lots of expensive rebuild. It usually overheats when really cained. Details:- Engine - RD350 YPVS (F2) 1WT approx 1990 Carbs - Mikuni 28mm, Pilot jet 27.5 (stock), needle clip 2nd groove down (stock) main jet 260 (180 stock) Power jets 55 stock left hand 50 stock right hand carb Exhaust - FMF Fatty front pipes, Power Core 2 silencers Air box - standard with snorkel removed and hole cut to rear of lid Filter - standard Ignition timing - standard non adjustable Reeds - FMF fibre Plugs - was using BR9EG but going to try BR8EG Anyone else got any experience ? Quote Link to comment Share on other sites More sharing options...
rzcolobanshee Posted July 22, 2005 Report Share Posted July 22, 2005 Mains seem really really small, I'm running 290's at 5000ft elevation and 26mm carbs, I would guess you need to be around 340 or so Quote Link to comment Share on other sites More sharing options...
quadguy214 Posted July 22, 2005 Author Report Share Posted July 22, 2005 I should point out that the original RD carbs that I am using are power jet carbs. The power jets are 55/50 and add to the main jet (260) when flat out giving 315/310. These have cause me no end of hassle and am going to try a set of non-power jet RD carbs with bigger main jets. Just wondered if other RD/RZ engine users have used the power jet carbs ? Quote Link to comment Share on other sites More sharing options...
Master of Faster Posted July 22, 2005 Report Share Posted July 22, 2005 (edited) I have no experience in this but it seems to me that if the power jets only add fuel at WOT then the result would be a really lean midrange with the 260 main and the needle on the second clip. If it were me I would try raising the needle or just going with a non power jet carb like you were saying. It would be much easier to get jetting advice then. Edited July 22, 2005 by Master of Faster Quote Link to comment Share on other sites More sharing options...
Rare Scottish Tree Badger Posted July 22, 2005 Report Share Posted July 22, 2005 Might be worth investing in an EGT monitor. ... I wouldn't advise changing to BR8s until you get your temperatures down. You using this for MX? Rare. Quote Link to comment Share on other sites More sharing options...
switchblade Posted July 22, 2005 Report Share Posted July 22, 2005 I all most sound like an air leak. Quote Link to comment Share on other sites More sharing options...
sheefreak Posted July 22, 2005 Report Share Posted July 22, 2005 So what happens when you say it blows after 3 hrs, what do the pistons look like? http://www.mztech.fsnet.co.uk/workshop/wrk_piston.html This site may help you diagnose your problem a little better. Spark plugs and pistons are tell tale for reading problems such as yours. Quote Link to comment Share on other sites More sharing options...
cbn70 Posted July 22, 2005 Report Share Posted July 22, 2005 Sounds like there is a problem that has not been fixed, since you engine keeps on blowing up. First thing to do is a leak down test on the engine to see if there are any leaks. If there are no leaks, then it is time to start doing jetting runs and looking at your spark plugs to see if your jetting is correct. If your bike is jetted correctly and there are no air leaks, it should not blow up every three hours. hope this helps Quote Link to comment Share on other sites More sharing options...
cbn70 Posted July 22, 2005 Report Share Posted July 22, 2005 Almost forgot, if you are using the stock carbs off the rz, you need to plug off the oil injection ports(pull out the barbed fittings and install brass plug, or put rubber boots on them) or they will cause the engine to go lean. Quote Link to comment Share on other sites More sharing options...
quadguy214 Posted July 22, 2005 Author Report Share Posted July 22, 2005 Yeah do sometimes use it for MX and not so much of a problem due to shorter duration of racing say 3x 15/20 min races, but during endurance (3hr) events usually when the problem happens although it did blow for the first time at MX. It is always the LEFT hand piston (5 times now !!!) never the right. I don't have any pictures but on the crown (top surface) of piston at the front looks as though the piston material has melted/crumbled away usually exposing the top surface of the top ring. It doesn't actually seize proper. Have completely rebuilt the engine several times with all new crank case seals and all rubber boots etc have no cracks in the on the inlet so I don't think I've got air leaks. Back to spark plugs - the RD engine that i have should run a BR9 as standard but I know a stock Banshee engine uses BR8. What effect would going even lower have say BR7 ? The engine has always failed at WOT not between 1/4 to 3/4 so its gotta be down to the mains. I don't hold it WOT for very long, just for a few seconds. Now after many trials I am inclined to think it actually may be on the rich side which is not as bad as being lean but can still cause overheating of the engine when its being thrashed. My next steps are simply to use NON-POWER jet carbs with say 320 mains and BR8 plugs. Also I am wondering, is it simply a cooling issue ? With the RD engine being raced in a quad surely it doesn't get the same cooling effect as when used in the road bike (due to slower speeds) Currently using standard banshee rad and standard water pump that is fitted in the RD engine (pump also recently serviced). The cylinder head is standard RD YPVS. Maybe get oversized rad, or inline cooler that fits in the hose (but can't see that they do much) and/or cool head. Quote Link to comment Share on other sites More sharing options...
rzcolobanshee Posted July 22, 2005 Report Share Posted July 22, 2005 May want to check to see if the thermostat is opening (i completely removed mine) Quote Link to comment Share on other sites More sharing options...
quadguy214 Posted July 22, 2005 Author Report Share Posted July 22, 2005 Sorry for rambling on !! Yeah the oil feeds to the carbs are plugged. Quote Link to comment Share on other sites More sharing options...
quadguy214 Posted July 22, 2005 Author Report Share Posted July 22, 2005 Yeah I've also done the same some time ago and removed the thermostat. Quote Link to comment Share on other sites More sharing options...
quadguy214 Posted July 22, 2005 Author Report Share Posted July 22, 2005 One other thing I forgot to mention. The last time the left piston failed, when I dissassembled the engine, I found that the FMF reeds on the left hand cylinder were severely damaged and been blown back through the reed cage towards the carburettor. Trouble is, did the reeds fail first the casue piston to fail or the other way round !?? Quote Link to comment Share on other sites More sharing options...
Rare Scottish Tree Badger Posted July 22, 2005 Report Share Posted July 22, 2005 Yeah do sometimes use it for MX and not so much of a problem due to shorter duration of racing say 3x 15/20 min races, but during endurance (3hr) events usually when the problem happens although it did blow for the first time at MX. Do you run with no tickover? If so, which method do you use ... backing off the idle screws, or richening the air mixture screws (pilot circuit)? ... I'm not saying this is your cause of top end failure, but it will make a difference when coming off the throttle after WOT to no throttle. It is always the LEFT hand piston (5 times now !!!) never the right.I don't have any pictures but on the crown (top surface) of piston at the front looks as though the piston material has melted/crumbled away usually exposing the top surface of the top ring. It doesn't actually seize proper. Excess heat, but you know that. ... Does the other piston ever show signs of overheating? Have completely rebuilt the engine several times with all new crank case seals and all rubber boots etc have no cracks in the on the inlet so I don't think I've got air leaks. Better to do a leak down test on the rebuilds so you can say "I don't have an air leak". (Obviously, one can develop). Back to spark plugs - the RD engine that i have should run a BR9 as standard but I know a stock Banshee engine uses BR8. What effect would going even lower have say BR7 ? That plug will be too 'hot' for your riding conditions. ... It's working temperature is a lot lower and it won't remove enough heat. I would stick with the 9s, you don't have an increased compression, but you will be running hard at mostly between sea level and 1000ft I guess. The engine has always failed at WOT not between 1/4 to 3/4 so its gotta be down to the mains. I don't hold it WOT for very long, just for a few seconds.Now after many trials I am inclined to think it actually may be on the rich side which is not as bad as being lean but can still cause overheating of the engine when its being thrashed. As mentioned earlier, that needle setting seems lean for 1/4 to 3/4 throttle which is going to add heat when you're in that range. ... Have you done any plug chop runs? Have you tried bigger mains than the 260s with the power jets? You would have noticed performance problems and maybe plug fouling if you'd been running too rich. My next steps are simply to use NON-POWER jet carbs with say 320 mains and BR8 plugs. Arm yourslf with 310s to 340s, but I still say stick with the 9s 'till you sort the overheating out. Also I am wondering, is it simply a cooling issue ? With the RD engine being raced in a quad surely it doesn't get the same cooling effect as when used in the road bike (due to slower speeds)Currently using standard banshee rad and standard water pump that is fitted in the RD engine (pump also recently serviced). The cylinder head is standard RD YPVS. Maybe get oversized rad, or inline cooler that fits in the hose (but can't see that they do much) and/or cool head. You're also putting a lot more stress on the engine than it was designed for. (More weight to pull and MX/ Enduro are tough on the motor). RD or Banshee gears? Any of those cooling aids that you mention are going to be an improvement over stock. ... Some other things that are worth thinking about are the Pro Design impeller (water pump) for reliability and increased flow. And some better coolant, such as Engine Ice or Redline Water Wetter. (I use Engine Ice and am about to get the Impeller). One other thing I forgot to mention. The last time the left piston failed, when I dissassembled the engine, I found that the FMF reeds on the left hand cylinder were severely damaged and been blown back through the reed cage towards the carburettor. Trouble is, did the reeds fail first the casue piston to fail or the other way round !?? Most likely after IMO, as you would have felt the lack of performance with blown out reeds. Did the reeds ever fail like that with any of the other engine failures? What premix ratio do you run, and what octane fuel? Rare. Quote Link to comment Share on other sites More sharing options...
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