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Has anyone had any experience with a rear sprocket with less than 38t?

 

My xr4 has a pumper carb, stage 1 hot cam, 416 kit and white bros which gives it plenty of get up and go but still only cruises at 55mph at 5k rpm.

 

Right now it has a 16t counter sprocket and 38t rear with 17" sm wheels. If only there was a 6th gear......

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If it were my bike, I'd but the cheapest steel rear sprocket I could find.
Id try 5 teeth smaller then maybe 3 more smaller.
 

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6 hours ago, arthur6 said:

If it were my bike, I'd but the cheapest steel rear sprocket I could find.
Id try 5 teeth smaller then maybe 3 more smaller.
 

If it was your bike you would put octane booster in it and then claim to everyone that it was all that was needed.

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classic   octane booster does not give more power.... simply creates longer carbon threads in the fuel which makes the fuel more stable under high compression with out pre detonation or pinging.  ie. the higher compression ratio the higher the octane rating needed. look it up theres plenty of info on the topic.

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the smaller wheel size is what will be affecting the top end speed. I know its only an inch but it makes all the difference  tire tread is another factor road slick as to a knobby

sounds to me like you could go at least a 35 tooth on the rear 37t is the smallest I can find on short notice.

http://www.ebay.com.au/itm/GENUINE-HONDA-REAR-SPROCKET-37T-XR400M-/172855067181?epid=1650882158&hash=item283ef7022d:g:L94AAOSwMmBVwXL2

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the smaller wheel size is what will be affecting the top end speed. I know its only an inch but it makes all the difference  tire tread is another factor road slick as to a knobby
sounds to me like you could go at least a 35 tooth on the rear 37t is the smallest I can find on short notice.
http://www.ebay.com.au/itm/GENUINE-HONDA-REAR-SPROCKET-37T-XR400M-/172855067181?epid=1650882158&hash=item283ef7022d:g:L94AAOSwMmBVwXL2



Thanks for looking man all I could find was a 38t, any other sites/sources you recommend for a 35 or 36t?

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Alright - this has my interest as well. I take my XR on about 65% road and then on the back roads and some pasture and trails. I have thought about trading out the rear drive sprocket for one with fewer teeth and I see many that are sets of front and rear sprockets as well.

 

So what is the standard front/rear setup on the '99 XR400?  If I want to cruise at 65 mph without over revving the engine what would be the suggested sprocket teeth to get?

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After playing with the gearing commander above ^^^^ I think I'm going with a 16/38 combination with a new X-Ring chain. It gets me a smooth 60MPH at 5Krpm without loosing much of that low end grunt. 

http://www.ebay.com/itm/PBI-XR-16-38-Chain-Sprocket-Kit-for-Honda-XR400R-1996-2004/322346246804?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

Before I pull the trigger does anyone see an issue with the setup I'm looking at?

Edited by ThumperCurtis

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I currently have the 16 and 38 setup and I ride 90% street with street wheels
And tires. Even with a bore kit, carb, exhaust and cam it's a little laggy in first but Curtis is dead on with the cruising speed and rpm

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15t - 40t works fine I had 15 40 on my xr400 a while back and it was great for open road (100kmh) or 62.13 mph for you yanks but not so great on the dirt. I ended up changing to 14t -45t now comfortable at 80kmh on the open road (49.7mph) and much better out bush lifting the front wheel again.

16 - 38 sounds a bit extreme if you have a standard set up(wheels tyres ext) would be ok for top speed but will lag bad on take off and in the bush. that being said I don't think a 16t sprocket will fit with oem case saver.     here in aus the 400r came stock with 15t -45t a bad combination for chain wear.

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plastic shroud that goes over the sprocket??????????  chain guard??  my front sprocket cover is made of steel as is the case saver under it both oem. is that what your talkin about???

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Well dang - you're totally right @vicxr400. I learn something new each day :-). Yes it is the front sprocket guard and it is metal not plastic. I had only looked at the cover and never physically examined it.  

 

I will have to check it out when I get my 16T to see if it has clearance.   

 

ImageUploadedByThumper Talk1400456754.486131.jpg

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if your using the aftermarket case saver I think youl be right. the oem case saver was made to suit a 15t sprocket with not a lot of clearance. 16t might fit but its going to be real tight still doubt it will fit. give it a go and let us know how you got on.    you must be looking for a heap of speed going with a 16 on the front?? what size rear?

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Going 40T rear but I think I may try out the 15T with the 40T before trying out the 16T/40T combo. I'm turning it into an adventure bike so I need a little more top end for the tarmac. Most of the riding will be on blacktop and back roads with some pasture excursions. Nothing too extreme or trails that will require log hopping.

 

The new rear tire is a Pirelli Scorpion MT-90 110/80-18 sidewall rather than a 100/110-18 (factory) so its smaller diameter will take some of the speed out hence the new sprockets.     

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im using the stock tyre size 100/110- 18  and was running 15t - 40t  with that gearing it would sit on the highway @ 100kmh or about 62mph all day comfortable.

im now running a 14t-45t  same tyres now its only good for 80kph or about 50mph on the highway (that's at a comfortable rev range not screemin)

I don't know what the speed limit is in the states or your intended speed but I would say if the 15t-40t is not enough then 15-39 0r 38 should do the trick. if your looking at 60mph the 15t-40t should be fine. if your looking at 65 - 70mph go with 15t - 38t.

it seems that Honda released these bikes in 2 different factory gear settings (depending on country) some had 15-45 others had 15-40. my guess is that way they had a factory option for ether on or off road geared ready to go.    I hope the info helps  sprockets arnt that cheap here about $45 each. good luck and let us know what you ended up with and how it goes for you.  cheers

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i use for that reason 36 on my XR280 . But that sprocket i made from second hand near full metal scooter sprockets , just a little bigger

then the hub .

For the XR400 the other option would be the internal Gearing from the XR400 motard ND 08 from 2006 .

Thats much longer and give with  15/39 about 145 km/h at 6000 rpm

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