[rilusi]

zx9 motor is a slug
b1 motor 50k,,no chance of a wheellie..
just seems tired..carbs cleaned..news jets.what could it be..
exhaust is off a newer (96+zx7) smaller?
only the one ram air..the zx9r frame had the two tubes does this matter?
is it starving for air?
motor is in a 95 zx7?
any thoughts..
thanks in advance

 

[2000ZX9R]

zx9 motor is a slug
b1 motor 50k,,no chance of a wheellie..
just seems tired..carbs cleaned..news jets.what could it be..
exhaust is off a newer (96+zx7) smaller?
only the one ram air..the zx9r frame had the two tubes does this matter?
is it starving for air?
motor is in a 95 zx7?
any thoughts..
thanks in advance

Duh! 50,000 miles...

 

[parisdreams]

What are you comparing it to when you call it a slug?
1) it is a older bike and yes heavier and not as much power as the newer 1000
2) 50k miles says alot, you are right it is tired

Solutions
1) buy a newer bike
2) complete rebuild of motor (go ahead and do a big bore kit while your at it)

also R&D goes into exhaust although a zx7 exhaust will fit the 9 it isn't made for it. But that is not going to make much of a noticable difference.

 

[anarion55]

As said, PLUS - the ram-air only makes a significant contribution at 85+ MPH, so I'm guessing that's not the problem. You may not need a new engine r a rebuild -

Check the compression, valves, and clean/synch the carbs. New plugs as well.

THEN decide if it's a slug.

 

[rilusi]

i see

its 50k kilometers
carbs have been redone..and synced a few times..
i was thinking shims..valves?
rings?
i understand the ram air thing now..
guess its just the bottom end thats sluggish..
vibrates also,,
its what i have right now..and sweet to go get s newer ride...nest year mayby..
but for now..
thanks for the replys..guess in the fall i be doing a tear down motor rebuild..

 

[jbreit]

My 91 zx7 had 48K miles on it when I tore it down for an overbore kit...I figures it could use a rebuild anyway....it was in very very good shape....needed nothing.

Get those valve clearnaces checked (cam's stay in on those so its a cheaper/easier job), new plugs, and either check compression or do a leak down test while you are at it.

The pipe and jetting combination can make anything doggy. What did they do with the emissions stuff....? Is it geared tall maybe...?

 

[45acp]

Id say you need a valve adjustment and/or have ignition issues. Ive got that same motor only in the heavier 9R bike (you did say this is a swapped in 9R to 7R bike right?) and it will pull the front up HARD in first with no clutch. Im 200-205 lbs and with my balls on the tank it will power up with stock gearing. If im not mistaken, stock 7R and 9R had the same front sprocket but the rear was -2 on the 7R.

Either way, something aint right.

 

[45acp]

Id also like to add... hold off on the rebuild. You've basically got a Honda Accord with 30k miles on it. I think you have other issues. One of the reasons why i got a ZX9B, among other things, is after a buddy of mine tore one down after 90k miles he said it was a complete waste of time. Everything was supertight and in spec.

 

[rilusi]

hmmm

emmision crap..blocked off..
front stock gearing..rear +2(46t)
yeah in zx7 Lframe..
sounding too me like valves
thanks again..am looking for a better pipe..
what would new plugs cause..they were changed about 2k ago?
i was thinking it might be jetted to hihg(need smaller jets?
it has new 190 across the rack..but i guess thats mostly affects higher speeds! float hieght and new float needles ..carbs are great!! didnt change the ilot jets..cleaned though..and adjusted and re-o-ringed the air fuel screws..how many turns you think! would this affect it?
west coast sea level!
thanks again losing my religion here!

 

[anarion55]

its 50k kilometers
carbs have been redone..and synced a few times..
i was thinking shims..valves?
rings?
i understand the ram air thing now..
guess its just the bottom end thats sluggish..
vibrates also,,
its what i have right now..and sweet to go get s newer ride...nest year mayby..
but for now..
thanks for the replys..guess in the fall i be doing a tear down motor rebuild..

If the compression is good, then the rings are ok. Is the bike jetted correctly for your altitude/pipe/filter combination? When you say the carbs have been "redone" did they screw around with the jets?

+1 on checking the emissions stuff.

 

[45acp]

190 main jets are stock. If i remember right 4 turns out on the air screws.

I still say check your valve lash first.

 

[yorkie]

So I take it you've put a nine engine into the 7, a really good mod, but while you can use the 7's exhaust system you will be restricting the engine, so fit a nine one.
Also get the valves shimmed there easy enough to do on these engines with a screwdriver and a magnet on a stick, and a load of shims in the range of 2.60 to 2.90.

You will also need to make sure the ram air is sealed and working correctly as this can choke the engine above 40 mph.

Here is a web site you will find very usefull. http://homepage.ntlworld.com/webzxr/zxr750r/