Jammin JPX 21 Plus ( new)
02-07-2010, 05:45 PM
#181
so if you don't shim the head what exactly happens that they don't last 2 gallons? the jammin's are some of the most underated motors available today. i took the head off just to locktite the screws. i sealed around the carb and backplate and locktited those screws. i did the drake/cyrul break-in and ran the motor for 2.5 gallons with 20%, sold it and now it has been running strong on 30% another gallon. the guy that bought it from me took off the backplate to check it, absolutely no play in the rod, no leaky bearings and no carb issues. which is more important, proper tuning or shimming the head? any motor not properly tuned will die early, a blanket statement that you "have to" add a shim or a motor wont last 2 gallons does not help anybody when there are so many other variables that determine engine life.
02-08-2010, 06:01 AM
#182
Tech Master
iTrader: (4)
I ran my first JPX with stock head shimming and 30% fuel until I found evidence of detonation. After that I added a shim and also added one to my second engine before break in. I am starting to think the stock plug is pretty cold. It is too bad there is no good way to measure the heat range between different brands of plugs.
02-08-2010, 08:29 AM
#183
I ran my first JPX with stock head shimming and 30% fuel until I found evidence of detonation. After that I added a shim and also added one to my second engine before break in. I am starting to think the stock plug is pretty cold. It is too bad there is no good way to measure the heat range between different brands of plugs.
actually there is a way to check the plugs....the diam of the hole and the thickness of the wire....its hard to tell and you need every plug in front of you to make the decipher but it Is possible to tell which plug is what if you take the time and look CLOSELY.
02-08-2010, 08:58 AM
#184
I ran my first JPX with stock head shimming and 30% fuel until I found evidence of detonation. After that I added a shim and also added one to my second engine before break in. I am starting to think the stock plug is pretty cold. It is too bad there is no good way to measure the heat range between different brands of plugs.
02-08-2010, 10:45 AM
#186
no, i run these engines on 30% with only 2 shims ( 0.4mm of shims total) ...the key is when you remove the shim to make sure you richen the needles and then retune once warmed up.....As a rule removing shims will cause the tune to go slightly leaner......
However unless your running Picco plugs do not remove the thrid shim...OD and OS plugs wont like the higher compression and will not give you the same performance as the Picco plugs.....To really see what these engines can do you really need to be running genuine Picco turbo plugs...the Picco plugs are very robust and durable and will operate perfectly with the higher compression, OS and OD plugs will just cause you issues.......From my own testing OS plugs are the worst and will fail the quickest, OD are a little better but still not as good as the Picco's..... FYI I run OS and OD in many other engines with great results, however the Picco engines are unique and truly run best with Picco plugs...
02-08-2010, 10:56 AM
#187
no, i run these engines on 30% with only 2 shims ( 0.4mm of shims total) ...the key is when you remove the shim to make sure you richen the needles and then retune once warmed up.....As a rule removing shims will cause the tune to go slightly leaner......
However unless your running Picco plugs do not remove the thrid shim...OD and OS plugs wont like the higher compression and will not give you the same performance as the Picco plugs.....To really see what these engines can do you really need to be running genuine Picco turbo plugs...the Picco plugs are very robust and durable and will operate perfectly with the higher compression, OS and OD plugs will just cause you issues.......From my own testing OS plugs are the worst and will fail the quickest, OD are a little better but still not as good as the Picco's..... FYI I run OS and OD in many other engines with great results, however the Picco engines are unique and truly run best with Picco plugs...
However unless your running Picco plugs do not remove the thrid shim...OD and OS plugs wont like the higher compression and will not give you the same performance as the Picco plugs.....To really see what these engines can do you really need to be running genuine Picco turbo plugs...the Picco plugs are very robust and durable and will operate perfectly with the higher compression, OS and OD plugs will just cause you issues.......From my own testing OS plugs are the worst and will fail the quickest, OD are a little better but still not as good as the Picco's..... FYI I run OS and OD in many other engines with great results, however the Picco engines are unique and truly run best with Picco plugs...
Last edited by RC-ZOMBIE; 02-08-2010 at 11:46 AM.
02-09-2010, 07:49 AM
#188
Tech Master
iTrader: (4)
no, i run these engines on 30% with only 2 shims ( 0.4mm of shims total) ...the key is when you remove the shim to make sure you richen the needles and then retune once warmed up.....As a rule removing shims will cause the tune to go slightly leaner......
However unless your running Picco plugs do not remove the thrid shim...OD and OS plugs wont like the higher compression and will not give you the same performance as the Picco plugs.....To really see what these engines can do you really need to be running genuine Picco turbo plugs...the Picco plugs are very robust and durable and will operate perfectly with the higher compression, OS and OD plugs will just cause you issues.......From my own testing OS plugs are the worst and will fail the quickest, OD are a little better but still not as good as the Picco's..... FYI I run OS and OD in many other engines with great results, however the Picco engines are unique and truly run best with Picco plugs...
However unless your running Picco plugs do not remove the thrid shim...OD and OS plugs wont like the higher compression and will not give you the same performance as the Picco plugs.....To really see what these engines can do you really need to be running genuine Picco turbo plugs...the Picco plugs are very robust and durable and will operate perfectly with the higher compression, OS and OD plugs will just cause you issues.......From my own testing OS plugs are the worst and will fail the quickest, OD are a little better but still not as good as the Picco's..... FYI I run OS and OD in many other engines with great results, however the Picco engines are unique and truly run best with Picco plugs...
Did you try all of the OD plugs or just the 97t?
02-09-2010, 08:08 AM
#189
You killed 2 Picco plugs and had detonation on stock shimming....I hate to say this, but honestly you must have had the engine too lean for it to do that...Not intending to pick at you or anything like that........Back when i got my first EVO 2 I did something similar as well.......... With stock shimming the compression is nowhere near high enough to cause detonation on 30% unless the mixture is too lean, killing plugs is also from being too lean as well....... With a proper tune nothing runs as nice in these engines as a genuine Picco plug, I kid you not either...I wish it wasn't true as OD plugs are cheaper and easier to find...but unfortunately they are nowhere near as good as the Picco's.... And yes I have run more then the OD 97 in them, I have modded and run many dozens of these engines over the years...
02-09-2010, 08:17 AM
#190
Hey all: the new jammin jpx .21 plus engine looks realy good what i want to know is are the new plus engines still picco based as the old ones were? Thanks for the info and good luck to the jammin team in 2010 
02-09-2010, 08:18 AM
#191
All the Picco turbo's work well...we generally run the OFNA Picco Med turbo ( P6TH)
02-09-2010, 08:19 AM
#192
Yes they are Picco based, and I will have modified JPX engines ready to go for next week if anyone is interested.... they will sell for $300.00 modified with hand fitted piston...can also put together a combo with a JP4 tuned pipe, glowplugs and M2C variable weight 4 shoe clutch combo...
02-09-2010, 09:02 AM
#193
The odd thing with Picco is that the shim means nothing, Picco is notorious for inconsistant shimming on their engines , sometimes they send extra shims, sometimes they don't , and they don't always send the same amount of extra shims with every engine......sometimes they have no extra shim, sometimes they have 1, sometimes they have 2 and the odd time they even have 3 extra shims......However the ideal operating compression of the engine doesn't change, and stock shimming of 0.5 mm is more then plenty enough to run 30%, i run a total of 0.4 mm total shims and I always run 30% and my engines run like a top.....If you notice any detonation or you are losing plugs you need to richen your mixture, not add more shims...
All the Picco turbo's work well...we generally run the OFNA Picco Med turbo ( P6TH)
All the Picco turbo's work well...we generally run the OFNA Picco Med turbo ( P6TH)
02-09-2010, 09:11 AM
#194
Tech Master
iTrader: (47)
I run one of Neal's(Maximos) Clocked JPX .21 engines
with .4mm of shims. This sets the pistion to headbutton
clearance at .6mm. It has had almost three gallons of
30% ran through it now and still has the original glow
plug. I just pulled the head button off to confirm how
many shims I was running and to get a squish measurement.
The top of the piston and head button show no carbon
buildup and the glowplug reading looks great. This engine
was broke-in properly and the rod was replaced. The rod
really didn't need replacement but I did it anyways to be
safe.
Anyone thats only getting two gallons out of these engines
had better learn how to break an engine in properly or pay
someone that offers engine service to do it for them.
As far as anyone blowing the Picco glowplugs one after
the other, LEARN TO TUNE, your running your engines
way to lean. My JPX likes to run a little fat on the top
end.
Neal knows that I run the hell out of my engines and
he sure made my JPX one screamin engine.
with .4mm of shims. This sets the pistion to headbutton
clearance at .6mm. It has had almost three gallons of
30% ran through it now and still has the original glow
plug. I just pulled the head button off to confirm how
many shims I was running and to get a squish measurement.
The top of the piston and head button show no carbon
buildup and the glowplug reading looks great. This engine
was broke-in properly and the rod was replaced. The rod
really didn't need replacement but I did it anyways to be
safe.
Anyone thats only getting two gallons out of these engines
had better learn how to break an engine in properly or pay
someone that offers engine service to do it for them.
As far as anyone blowing the Picco glowplugs one after
the other, LEARN TO TUNE, your running your engines
way to lean. My JPX likes to run a little fat on the top
end.
Neal knows that I run the hell out of my engines and
he sure made my JPX one screamin engine.
02-09-2010, 11:39 AM
#195
Tech Master
iTrader: (4)
I do not think you understand. I had detonation with a non Picco (either OS or OD) plug. The stock Picco plug lasted through a heat cycle break in and never made it to a track before it died. On my 2nd engine the stock plug lasted until my first tank on the track (which means it never even went full speed on the straight). Forgive me if I do not want to spend $15 per plug to see if my luck changes. Did you try the OD 99T? I have ran the 97T and 77T and the 97T works great for me in cold weather. It does not seem as good in warm weather which makes me suspect the plug is too hot.
The time I had detonation the engine ran the best it ever did so it may have been lean but it seemed to be tuned about perfect. I saw no change in power or fuel mileage with the extra head shim.
The time I had detonation the engine ran the best it ever did so it may have been lean but it seemed to be tuned about perfect. I saw no change in power or fuel mileage with the extra head shim.