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Discussion Starter · #1 ·
The countershaft splines for the front sprocket have been ate away so its time to split the case, I was thinking about doing Hi comp Piston, and Stage 2 hot cam, anything else i should do while shes apart?
 

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First have crank checked to make sure i dosent need to be turned, Crank and rod bearings, new timing chain, new valves and seals, gasket kit, check clutches, go through tranny make sure it doesnt need any new bearings or gears, port and polish head. Check stator make sure all the winding look good if not i have i buddy that rebuils them it's alot cheaper than buying a new one let me know if ya need a rebuild on it.
 

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The crankshaft cannot be "turned" - it is a pressed together assembly. If the crank needs replaced or if there is any doubt about reusing it, just get a new Hot Rods crank. It is ultimately cheaper than repairing the present one and at least as good (if not better) than an OEM unit.

Have the head rebuilt, decarbonized, new valves and the seats re-cut. A new cam chain is a no brainer, new piston w/rings and probably rebore to the next oversize. Replace the clutch and of course inspect the transmission gears, shift forks and shift drum. Replace anything that is questionable. When examining the transmission gears, not only look at the teeth, but closely inspect the engagement dogs and slots. That's where most tranny problems pop-up. And don't forget the oil pump. If the engine has been run with dirty oil, incorrect rated oil, or if oil changes were done at less than the recommended intervals, then the oil pump may not be up to snuff.

These are not "simple" motors. They are very precise. Pay close attention to the measurements and wear limits as set forth in the service manual and good luck.
 

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Discussion Starter · #4 ·
Iam Pretty familiar with small engines and i have rebuilt Automobile Engines and A 5speed t5, Is this something i should do myself. The only Part That scares me is the tranny
 

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The tranny is simply a 5 speed constant mesh. Used in motorcycles since the beginning of time and used in race cars. It is durable, heavy and almost bullet-proof. Much simpler than a syncro-mesh or automatic transmission. If you can handle the motor part, the transmission should be a snap. The hard part of a motorsport transmission is separating the engine cases. Certain parts must be removed before attempting the operation and some special tools are required. Sometimes you can make do without the special tools, but extreme care must be used when makeshift tools are used that you do not damage an expensive component. Most of the time it is cheaper to get the required tool rather than replacing a damaged part, i.e. a flywheel puller is about $65 - a new flywheel is about $400. A service manual is invaluable.
 

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Discussion Starter · #6 ·
Well if have the right side case off,head,cylinder will have stator side case off tomorrow does anyone have instructions to split the case? Like what has to be removed and what can stay? What bore Size Should i go? Piston Brand? What Compression? Stroker Crank? crf450 cam chain?
 

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Remove the crank pinion gear, the clutch, kick starter, kick pinion, shift shaft, shifter pawl (everything from the right hand side) - remove the case bolts from the LH side - you want the crank and all the tranny parts to stay in the LH side.

Use a dead blow polycast hammer to drive on the RH end of the crank and tranny shafts to get the cases to break their seal. If you "whack" more than 4 or 5 times on each shaft and don't get the cases to break their seal, heat the cases with a propane torch (or put the engine in an oven) and heat to about 250 degrees, then try again. If still no go, buy (or fashion) a tool to pull the case while pressing on the end of the crank. You might be able to go to the local Honda shop and get them to let you watch while they separate an engine. Hondas are usually pretty easy - Yamahas require using a press.

Bore to .020 over whatever it is now. Piston is your choice. I like Numura, OEM, Athena and ProX for simple rebuilds. Wiseco, J&E, Wossner and others are for high perf only. Don't waste money on a high dollar piston unless you are going to push the motor to beyond it's normal limit. Stock compression, stock crank and stock cam chain (unless you are building for high performance). If you are building for hi-perf, don't stop with just a crank and piston - have the valves done, install Beryllium valve seats, install a hi-lift cam and new rocker arms. Dont forget to modify the intake and exhaust. Install a 1 or 2mm larger venturi carb and if you are going all out and want to win, have the transmission gears lightened, install a racing clutch basket, racing clutch, remove the electric starter and starter clutch. When you are done with the motor, start working on the chassis. To take advantage of the extra power the motor is making, you will need to install a racing rear axle carrier and eventually make other changes to improve handling and control.
 

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My error - the EX is not a kick start, but for the models that are, the kick start has to be removed.

Special tools include - large metric sockets, impact drivers, torque wrenches, calipers, micrometers, straight edges, valve spring compresser (with proper size valve cap end), snap ring pliers, flywheel puller, service manual, bearing separators, gear pullers, gasket removal tools, etc.

A note from the Clymer service manual: "The crancase (Figure 7) is a precision cast aluminum alloy. Do not hammer or use excessive force to separate the crancase. The case and sealing surfacesare easily damaged. The two case halves are aligned with dowels and sealed with a gasket." Special tools: "Crankcase reassembly requires the following Honda tools: 1. Assembly collar (part No. 07965-VM00100). 2. Assembly shaft (part No. 07965-VM00200, or 07931-ME4010B and 07931-HB3020A). 3. Threaded adapter (part No. 07965-VM00300 or 07931-KF00200)."

Note: part numbers 07965-VM00200 & 07965-VM00300 are reported as not available by Honda. Part 07965-VM00100 is about $20.50, part 07931-ME4010B is about $120.80, part 07931-HB3020A is about $56.50 and part 07931-KF00200 is about $13.00.
 

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Discussion Starter · #11 ·
Top End/Rh and Lh Covers are off. have removed most of rh side components/Do i need a special puller to pull the magnetic stator basket?
 

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Motion Pro flywheel puller 08-0086 available through most shops for about $14

If you are lucky enough to find a grade 5 or 8, 20mm bolt with the correct thread pitch - grind it flat on the end and it may be substutited for the purchased puller.

The service manual calls for a strap wrench to hold the flywheel while tightening the puller with a wrench - I usually hold the flywheel by hand and use a 1/2" air impact tool.
 

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Discussion Starter · #13 ·
i had no need to pull the flywheel anyway, the case is split, countershaft dissasembled, i took pictures of everything and practiced putting it back togerther, so now iam waiting on the countershaft that mess is over now. On to performance, i have settled on a 416 bore, Stage 2 Hot cam, Port on intake side, Port and Polish on exhaust side, New Valve Seats, 3 angle valve job, Hd Head Studs, What Full system pipe should i use? High Compression Piston or not? What Brand? Crank and rod are fine and so are the bearings, I have a k&n filter, going to be getting the powerlid too, Besides a rev box is there anything im missing or does this sound like a solid build, Also Getting Alum Airbox,And OS oiltank, maybe add the tranny cooler mod
 
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