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Discussion Starter #1
Ok. Let´s start a project. The goal is to get 20 rear wheel horsepower without sacrificing low end torque...



I got it dynoed today. 100 % stock, except the heavy rear tire (Maxxis Ceros 26x9.00R14). Result: not bad at all, better than I thought. The adverticed power for TW200 is 16 hp at crankshaft, now there is 15.65 hp at rear wheel. Measured on 3rd gear:







After Webcamshafts 80-261/grind:89 camshaft installation, 2nd test run is coming. Some carburetor tuning + free flow rear silencer is coming too.



I have not seen any measured fact/dyno results about TW camshaft modifications, so I need to do it.
 

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Sweet. It's about time someone did this. Were I wealthy I would have done it a long time ago. Would be interesting to see what one could get with all possible mods. TTR (225?) piston and cylinder/cylinder head?? Airbox and carb mods, exhaust, etc...
 

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Any way to display the torque numbers as well? The way I ride it's more important.....



What was that formula? HP/5050 ? Not working out.....



Bag
 

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Discussion Starter #8
TQ=HP*5252/RPM



TQ @ 2100rpm = 6*5252/2100 = 15.0

TQ @ 3200rpm = 10*5252/3200 = 16.4

TQ @ 4350rpm = 14*5252/4350 = 16.9

TQ @ 5400rpm = 15.65*5252/5400 = 15.2

TQ @ 6200rpm = 14*5252/6100 = 12.0


Thanks pgilles. I calculated that the highest power was at about 6800 rpm (it is taken with 3rd gear). http://www.it-ideas.net/bike/calc.htm
 

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Sorry, there is a calculation mistake.

M = 9550 * P / n



M => torque

P => power in kW

n => rpm


Indeed there is. The formulas are correct though, just not my TQ numbers. I was thinking bottom of graph was rpm, but it is actually kph! No wonder I didn't see 9500rpm on there and such nice torque numbers
haha
 

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But you have to keep in mind, that these calculated values are not allways the "real world" values.



@ TeeWee

Why do they had tested in the 3rd gear?

Normaly they are useing on Dyno's the 4th on a 5-speed-transmission or the 5th on a 6-speed-transmission.



You will need the outer perimeter from your tyre and the transmission to make some calculations to get the real engine rpm.
 

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Discussion Starter #12
But you have to keep in mind, that these calculated values are not allways the "real world" values.



@ TeeWee

Why do they had tested in the 3rd gear?

Normaly they are useing on Dyno's the 4th on a 5-speed-transmission or the 5th on a 6-speed-transmission.



You will need the outer perimeter from your tyre and the transmission to make some calculations to get the real engine rpm.


I don´t know, the bench is meant mainly for more efficient motors, so maybe he got it more stable in 3rd gear.



The calculator I linked measures the circuit diameter of the tire from the tire overall diameter (Maxxis is adverticed it 26.0": http://www.maxxis.com/MotorcycleATV/ATV-Utility/MU07-Ceros-Front.aspx). So I think the calculations are correct.
 

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I don´t know, the bench is meant mainly for more efficient motors, so maybe he got it more stable in 3rd gear.



The calculator I linked measures the circuit diameter of the tire from the tire overall diameter (Maxxis is adverticed it 26.0": http://www.maxxis.com/MotorcycleATV/ATV-Utility/MU07-Ceros-Front.aspx). So I think the calculations are correct.
Ups, sorry, I haven't seen that the rpm is posted.

9550 for P in kW

7022 for P in HP



TQ @ 2100rpm = 6*7022/2100 = 20.06Nm

TQ @ 3200rpm = 10*7022/3200 = 21.94Nm

TQ @ 4350rpm = 14*7022/4350 = 22.60Nm

TQ @ 5400rpm = 15.65*7022/5400 = 20.35Nm

TQ @ 6200rpm = 14*7022/6100 = 16.12Nm



I am sure, these values are not correct.

These are just theoretical values.



The org. engine does have:

15Nm @ 7000rpm

16Nm @ 6500rpm

-> These values are from Yamaha (from 2 different brochure).



If I make the same calculation based on this values:

15Nm * 7000rpm / 9550 = 12.00kW -> 14.95 HP

16Nm * 6500rpm / 9550 = 10.89kW -> 14.81 HP







It's allways better to have a chart with both lines for HP and Nm.

These calculation isn't allways correct.
 

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Ups, sorry, I haven't seen that the rpm is posted.

9550 for P in kW

7022 for P in HP



TQ @ 2100rpm = 6*7022/2100 = 20.06Nm

TQ @ 3200rpm = 10*7022/3200 = 21.94Nm

TQ @ 4350rpm = 14*7022/4350 = 22.60Nm

TQ @ 5400rpm = 15.65*7022/5400 = 20.35Nm

TQ @ 6200rpm = 14*7022/6100 = 16.12Nm




I am sure, these values are not correct.

These are just theoretical values.



The org. engine does have:

15Nm @ 7000rpm

16Nm @ 6500rpm

-> These values are from Yamaha (from 2 different brochure).



If I make the same calculation based on this values:

15Nm * 7000rpm / 9550 = 12.00kW -> 14.95 HP

16Nm * 6500rpm / 9550 = 10.89kW -> 14.81 HP







It's allways better to have a chart with both lines for HP and Nm.

These calculation isn't allways correct.


The bold calculations above are INCORRECT. This was MY mistake I made in an earlier post (which I edited). I assumed the bottom of the dyno graph was RPM, but it is actually KPH.



I'll try to give this another shot. Please correct me as I'm kind of rushing...



It should look like this:

Engine rpm in 3rd gear,

([email protected])= 2682rpm

([email protected])= 4087rpm

([email protected])= 5556rpm

([email protected])= 6897rpm

([email protected])= 7919rpm



TQ @ 21kph = 6hp*5252/([email protected])= 6hp*5252/2682= 11.7 ft-lbs

TQ @ 32kph = 10hp*5252/([email protected])= 10hp*5252/4087= 12.8 ft-lbs

TQ @ 43.5kph = 14hp*5252/([email protected])= 14hp*5252/5556= 13.2 ft-lbs

TQ @ 54kph = 15.65hp*5252/([email protected])= 15.65hp*5252/6897= 11.9 ft-lbs (~16.1 N-m)

TQ @ 62kph = 14hp*5252/([email protected])= 14hp*5252/7919= 9.3 ft-lbs
 

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Discussion Starter #15
New muffler ordered: M.S.R Tondo, stainless steel, from Italy.



 

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Any more dyno updates?
 

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Discussion Starter #17
Not yet, sorry. I am waiting for the new muffler and I´m thinking should I change the valve springs too. The shape of the camshaft is not so sharp, maybe the original would work well too. I already have the Valve Spring Kit With CrMo Retainers Beehive (Race), but installing them means that the engine should take off and the cylinder head too.
 

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Yeah, that would be a pain to do. If there's any concern of the stock springs not controlling the new cam tho, might be better to be safe than sorry.
 

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Discussion Starter #19
The new cam is in now. I changed the valve springs too to "Valve Spring Kit With CrMo Retainers Beehive (Race)"

I changed the main jet from 114 to 120, but I think it still runs quite much too lean now. It feels good, there is more power in lower gears, but when you´d need torque on 4th and 5th, it won´t response properly any more. So, maybe something like 126 or 130 jet would be ok.



Some project pictures:



Cover off:



Magneto cover off:



Camshaft chain tensioner off:



Camshaft bolt off:



Sprocket off:



Head off:



Locking plate off:



Pulling the valve shafts off (the plate what I used for support, is from trash can, that´s why it looks so weird):



Exhaust valve rocker arm off:



Intake valve rocker arm off:





To be continued (no more pictures allowed)...
 

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Discussion Starter #20
Cam off (with end bearing):



Valve compressing:



Valves grinded:



Valve rod seal off:



Bottom cup off:



New spring and retainer (stock springs are double (inner and outer), these are single progressive):



New head gasket and rubber seal for guide:





And isnstallation is very much everything back which you have took off.
I had problems with the camshaft chain, if was jumped off the lower sprocket during the installation. But I managed to get it back without taking the magneto off. There is good manual (tw200mainmanual.pdf) in the net, which helps to found correct torque numbers e.g. for the head bolts and instructions how to tighten the camshaft chain.



New muffler:

 
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