Overdrive 5th gear

[jasper1252]

Is there anyone who has ran mikes 5th gear overdrive? What difference did it make?

[inxs]

- rotation is 24/23 = 4.4% higher at all speeds in 5th gear - you could also say that engine rotation is about 4.4% less
- its possible that you may have to be more careful setting the clutch afterwards, a 1 piece push rod helps

[yamaman]

Pamcopete has made a great gearing chart that includes Mikes 5th gear
http://xs650temp.proboards.com/index...y&thread=11068

[jay760]

I don't run the 5th gear but I do run an 18 tooth front sprocket, I'm not sure what ratio it gives but does lower the rev's right down, unless you are rebuilding the engine this is a far easier way.

[xsjohn]

Being light and having my engine set up correctly for tall gears I settled on 18/29 for good all around cruising.......can stay in 4th more now and off the bad 3rd and 5th gears that can shed their dogs ........with tall gears the timing needs to be retarded a bit...factory advance is for all the high revs and hurts the smooth lower rev performance..18/30 was ok but spun a bit more than I liked on the express.......8-1 compression made mine run just the way I like it.....no noises and quite smooth.......just rolled 76 thousand on the stock pistons and clearances are good....had some crank problems when I first got the bike but as ratty as it used to run that was no wonder......these will run on like a toyota if you get rid of the ratcheting and control the heat.........if not they won't.......

Would like to try mikes 5th with 18/30 but every time I think I will try it I worry for 4th which is perfect now.......was forced into 5th too much with 18/30....and the 8-1 just plain smoothed out everything on my 80.......goes all day in the summer without any engines noises.......walaha......

3500-3600 @ 65 in 5th
3700-3800 @ 60 in 4th

Oh and 230 Degrees is a good target for max "summer" cruising cylinder temperatures....most are 30-40 or more above that....just think how your car clatters when its overheating and the water is pouring out........wouldn't take long to ruin a car engine at 260-270+ degrees....same goes for these too........

xsjohn

[tonyc]

John where did you get a steel rear 29 tooth sprocket? Thanks TC

[xsjohn]

Used a Martin #50 industrial sprocket and had the center machined then case hardened it......last forever then.......expensive......maybe mikes 30 with and 18 front and his 5th gear would be good too.....not sure what you are trying to do thought....if you plan to gear it tall the engine really needs to be set up a bit differently ....mine really does run nice 2000-4000 where I am mostly........still does the high revs but why......... xsjohn

[tonyc]

John I agree with you, I like to keep the rpm's down. I mainly ride on week-end day trips of about 300-400 miles and most is covered on 2-lane roads 55mph. I do also travel the freeways at 70-75 for 250 miles down to San Diego. Thanks TC

[xsjohn]

I usually ride 65-70 on the express and 4th has most 50-55 back roads covered..some 3rd for the corners........you never told me wour weight.........and what epertise you have with the engine.......or the year or condition of the engine.......xsjohn

[bloodhound]

john what have you done to control the heat? just set up the engine correctly, added oil cooler. etc. I am thinking of running an external oil filter or cooler.

[curt698]

I have a 750, how is that going to affect the rpms at highway speed? Also noticed that the mikes gear won't fit the older bikes.

[xsjohn]

bloodhound ........oh god....went through all this on 650rider till I was blue in the face.......would think that most don't care or don't want to hear it again.....

Could cover maybe some important things I found for you..........

1. Oil cooler may help a bit........but the cylinders are the hottest place and the oil cooler won't effect the heat there what so ever....

2. Lowering the R/S hotter cylinder temperature will reduce the cylinder temperatures like 20+ degrees ...........

3. Using wind directing wings under the front forks and on the sides to direct the air over the cylinders lowers the running temps say 15+ degrees...

4. Good highway gearing probably helps some too.........

The combination of things is where it's at.........to reduce overall temps to say 225-230 max running cylinder degrees at 90 degrees ambient..........instead of 260-270+ or so normally found........ouch

I also reduced the compression to 8-1......lost just a bit of high rev power but everything else was a benifit...reduced ratcheting and smoother with reduce tenseness and no engine noises at operating temperatures........has to increase engine longevity and power loss when the engine gets hot.........at the end of a hot day it has as much power as it ever did....definate good trade off for me there for the summer............

curt698 .........same rpm...........may induce more vibes due to increased piston weight and or more compression....never ran a 750 on mine....I am a fly weight and old....already had all the powerhouse motorcyles I could stand......just a cruiser guy now...and mine will go faster than I care to go anyway....being 63 and all..... and still in one piece after 50 years of riding....

xsjohn

[bloodhound]

Okay, thanks john I am not a member on rider but I have seen so tech on wind deflection especially since those pipes on the right side block the fins. Good enough you always have good straight forward info.

[blue900]

John
Did you make the Wind deflector wings?
Even though its snow Boarding weather I'm wanting to get working on the Bikes!

[xsjohn]

Hey blue....Yea I made them........tried many designs....these look to me like they belong there....well mostly I guess...and the one up front works good too...don't forget to play with that one....the horn mount can be turned so it angles the horn back a bit to permint the air flow....the emblem mount has to be bent to angle the side wings outward.....not to hard just take your time to get the holes lined back up right....all together very noticeable improvement in temps.....made my side wings kinda small since I had the other heat improvements.........catch 22 there on the size....the bigger the better she says.....

Hard to think heat when you are freezing your ass.......and hello

xsjohn

[blue900]

xsjohn
Where did you get the material? I can come up with aluminum. I was thinking that horn was blocking air flow.
It has been damn cold snowing most days, Nice this afternoon about 35, the main roads are clear saw a guy on his enduro on the way home from work. I got at least 1.5 months before i can get mine out, Moved it in the snow once snow+xs650=bad bad idea.
Ron

[mule]

How do you run an 18T without sawing your shift shaft in half??

[bloodhound]

First, you have to remove that guard and keep the chain tight.

[blue900]

My 81 clears the shaft fine with the Guard removed as above, keep the chain adjusted properly. the 18 on the front is a huge improvment.

[xsjohn]

Blue.......Can't see how the material would matter...I had some carbon fiber from a hood and tons of the abs squares from another project.....carbon fiber is expensive as hell....just stiff for the side wings would be all or they could flutter.....my carbon fiber ones don't ....yea tried to ride a bicycle on the snow and ice when I lived in NFLD.......you know how that turned out......

xsjohn