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advise/help manic monster truck twin engine

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powernut View Drop Down
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    Posted: 07 November 2011 at 9:26pm
hi all new member i decided to buy a bit off a off road truck so bought a manic shumacher 1/8 scale with the twin .36 engine , i bought it second hand tbh , and not really knowing too mutch about these ,
problem  its running on 25 nitro fuel is this correct?(reason is ,its very heavy on fuel ,as it throws  more oil out from the exhaust it emptys the fuel tank very fast ,
 
next issiuse , the engine revs fine when lifted , but soon as i pop it on grass ,the egine wont rev up and wheels wont drive if faceing up hill (everything is free and brakes are not stuck on) im possiby thinking the clutch is buggard  or possible carn tunie is needed)
 
ive read the carb tuining thread , but hasnt improved the issiuse , i also removed the clutch , and looks ok? Confused
 any advise  or o these truck need to be set off on a flat surface , (i assumed these were dencent fun , not very underpowerd and slow Ouch
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Paul M View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul M Quote  Post ReplyReply Direct Link To This Post Posted: 12 November 2011 at 4:32pm
25% nitro should be fine.  Nitro engines by their nature are heavy on fuel anyway, so it's normal.  With a twin cylinder set-up, that problem is compounded.
 
The tuning guide should be all you need to get it running properly, but if you can't I'd suggest changing your glow plugs before you do anything else and get new fuel if the stuff you're using is older than a few months.  Then reset your carb needles to the factory settings.  It's the best place to start tuning from.
 
If you are spewing oil out of the exhaust and it bogs down easily, it suggests that you may be running too rich.  Some oil and residue from the exhaust is quite normal as not all the fuel is burnt and the lubrication is contained in the fuel, but too much unspent fuel coming from the exhaust suggests that your plugs are shot or too cold, or you are running too rich.
 
These trucks are designed for off-road running, not flat ground so there is no need to start them on a surface like that.  If you are still having problems after changing your plugs and fuel and then re-tuning, find yourself a club that races nitro and get advice or help from them to tune it.
 
Stick with it though; they are awesome fun when tuned properly and the power is immense.  Have a look at Youtube for the videos to see what the Manic is capable of when set up right.
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powernut View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote powernut Quote  Post ReplyReply Direct Link To This Post Posted: 12 November 2011 at 5:32pm
thankyou very mutch for the tips and advise , i ended up contacting the manufacter for techical advise and did buy new glow plugs , more fuel (same spec ) and found my engine sycro timing was out ,due to belt had slipped , least it starts and revs , but now ive a new issiuse,,
 
when warmed up , and i pull the throttle on  the vechical revs bog and clutch sounds as its slipping ,yet when i removed the clutch houseing i carnt see any wear and the spring is intact, double checked carb tunieing regards factory settings which are near as dam it correct ?do i buy a new clutch?
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Paul M View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul M Quote  Post ReplyReply Direct Link To This Post Posted: 13 November 2011 at 12:00am
A slipping clutch shouldn't cause the engine to bog.  Quite the opposite in fact; if the clutch is slipping the engine will over-rev because it is isn't engaging against the bell properly.  You'll get loads of revs with very little movement.  The engine bogging is possibly still a tuning issue by the sounds of it.  It could also be somewhere else on the transmission.  Have you free-wheeled the truck to make sure the belt, differentials and bearings feel free?  There shouldn't be lots of resistance if you turn the wheels by hand.  However, if you can actually HEAR something not right when it's running, something on the transmission could be binding.  Pop the belt off and turn the front wheels by hand; you should be able to feel if there is resistance, then do the same with the back.  If one feels different to the other, that's your problem area and you'll need to strip it down to check the following:
 
* None of the bearings are worn or frozen and that they are all seated correctly in their location points (check the transmission layshaft bearings, differential mount bearings and wheel hub bearings).  Give the bearings a quick blast of bearing cleaner and when they've dried out a dab of lubrication too before you reinstall them.
* None of the layshafts or driveshafts are bent.
* The differential outputs turn freely in the opposite direction to each other - they shouldn't feel notchy or gritty.
 
If it's none of these things, check the clutchbell whilst it is on the propshaft - make sure that the bell spins VERY freely and smoothly.  If not, change your bearings.  Also make sure that the bell does not have excessive play (i.e. movements in any other direction apart from rotation).  Make sure also that the engine is mounted in the correct position and that all mounting screws are properly tightened.
 
If that's all fine, the one other thing that I think it could be is the tension of the drive belt itself - if it has been tensioned too tightly, nothing will spin freely and the engine will struggle to turn the load.  You alter the tension by means of a sliding mount, usually on the underside of the chassis.  I can't remember exactly where it is on the Manic because I've not run mine for about 6 months.  I can't give you guidance on how tight or loose you need it; it is all done by feel.  The belt should be loose enough to let the transmission spin, but tight enough so it doesn't slip or flap around when the engine is running.  You'll probably need to make it slightly tighter than you would imagine - under load, especially at high speeds, the belts stretch ever so slightly which makes them looser.  You have it too loose and you'll be throwing the belt and losing all drive constantly.
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