rpm speed cross reference

[Dirt_McGert]

How high of a gear should I be in for travelling 25-30mph? I'm usually in fourth to save gas and lower the vibrations, but what happens if I'm in too high of a gear if I'm travelling slow? (say, if I'm going 10mph but I'm in third - what happens with the clutch/tranny - any slippage/damage?)

With the 16-tooth sprocket now, I shift from 1st to 2nd at around 15mph, from 2nd to 3rd at around 25, from 3rd to 4th at around 35, and 4th to 5th at around 45. With the 15-tooth stock sprocket, I would shift a tad bit sooner than now. But I'm just wondering if it's ok to be in that high of gear when travelling slower, not sure if it would cause any damage. Plus, being my first bike, I'm not exactly sure of how fast the engine is going with how it sounds. Does anyone have any sound clips of their 250 at certain RPM's?

[Jordan310]

Hmm.

Ive posted, and read posts. My bike seems to be a bit odder then some others I guess because my gears work something like this..

1st gear, up to about 15Mph, then I flip to 2nd.
2nd gear will hold me to about 30-35Mph, then I kick it up to 3rd.
3rd gear will get me up to about 45-47Mph, and then I pull it up to 4th.
4th will take 45Mph all the way up to 65, and then I kick up to 5th.
5th goes on forever, but starts to scream at about 75+ Mph.

I have had this bike for some time now, and have had it checked several times.
As the engine is from the DR250S (a dirtbike motor), I sort of ride it like one. This bike is pretty forgiving with the shifting, and RPM range.

I have noticed a slight oddity though. in 5th the bike for sure looses its pull, and really, I do have to drop down and then back up from 4th to 5th when hitting inclines on the highway to maintain 75Mph now. It seems to be getting worse. Whats more odd, is that I seems to have gained some low end torque, and its running a little stonger in the lower gears!

Anyone?

All parts for the big bore kit im installing should be here soon.
Im excited.

Have everything laid out. Big bore kit, hidden LED lights, new EMGO shorty mega muffler (modded), etc ..

Anyone know where I can get metal polished reasonably, and what K&N filter would work best on this carb?
As well, any suggestions on some slighty bigger or fattere tires for wet weather? Im always in the damn rain. Even when the engine gets water in the oil. (That sucks).

[jonathan180iq]

Did you swap the engine for a DR before the big bore kit or are you still running the standard GZ motor?

[Jordan310]

The DR is the same motor as the GZ. =)
No, Im running the stock 2007 GZ motor.

REVISION: I tested it after readinf the above posted gear topic, and on a straight away early on a very warm Miami street I started out and did this:

1st - up to 20Mph (shift)
2nd - up to 40Mph (shift)
3rd - up to 50Mph (shift)
4th - up to to 60-65Mph (Shift)
5th - 65Mph +

Is anyone else able to get the RPM's this high without making the engine bitch too much at you?
Im just wondinging even more what the big bore, and SPROCKET mod in particular are going to do.

[Easy Rider]

Originally Posted by Jordan310

1st - up to 20Mph (shift)
2nd - up to 40Mph (shift)
3rd - up to 50Mph (shift)
4th - up to to 60-65Mph (Shift)
5th - 65Mph +

Is anyone else able to get the RPM's this high without making the engine bitch too much at you?

Im just wondinging even more what the big bore, and SPROCKET mod in particular are going to do.

Probably not. Most of us know it's not a dirt bike racer and would like the engine to last a while ! :roll:

Are you doing this with the stock 15 tooth sprocket?
If so, OUCH!

I don't even get to those speeds (1st - 4th) WITH the extra tooth.........and don't think I'll try either, based on the sound the engine makes at the upper end.

[Jordan310]

These I do all the time with the 15 tooth give or take 2-3Mph.
Yea, the bike really does not scream at me too much either. Im not sure whats up with owners who cant seem to get past 50-60Mph.

Could it have to do with the fact that from the dealership to 3000+ miles Ive been riding it super fast, and pretty hard? I dunno.
My bike seems pretty able to handle the high revs I give it. Im going to have it fully checked again soon to insure that after 3000 miles I havent fucked anying up.

So far, .. the bike is strong though. Only a slight noticable loss in the upper gears (5th mostly). Dunno what thats about.
Again, the DR250S has the same engine, just a bit different gearing I think. The big bore kit should fit perfectly.

In any case, I think a loss in power is occuring because of the rainy season, Ive gotten water in the gas a few times, and the open air filter has gotten a bit damp.
Time to change it from the stock to a K&N. I woukd be more than grateful to anyone who can tell me which adaptor / KN filter (air) to use on the stock GZ250 carb.

Anyone?

[Dirt_McGert]

Is it ok to be in 4th gear travelling around 25-30mph? Note, I have the 16 tooth front sprocket, although it doesn't make that drastic of a difference in engine speed.

[Jordan310]

Uh.. yes. Its fine. Why you would want to do 20 in 4th is the real question. =)
You can do 10Mph in 4th if you want.

[Jordan310]

The sprocket (16 tooth), Im guessing is going to lower the RPM's on the top end, and allow you to reach 80Mph where you were just barely getting 75Mph (crossing fingers).
Actually for me, it will be .. trying to maintain 82-85Mph when my current top highway crusising speed is 78-79Mph.

After the big bore kit is in place, Ill pe pushing about 340cc's, and no doubt Ill hit 90Mph. Just a guess.
More torque by far, and quicker accel. for sure.

A pretty decent cafe racer / small crusier / city bike Im hoping.

[jonathan180iq]

Originally Posted by Jordan310

the DR250S has the same engine, just a bit different gearing I think.

Different transmission, different internals, different combustion chamber, different exhaust, different engine mounts....