I would like to know the advantages and disavantages of the hinson cylinder spacer for a 89 250r with a 86 piston. the reason i need to do this is the piston i got was for a 86 and i did not know that until after i had it bored and put it together and turned it over. the piston travels about a 1/4 inch out of the cylinder so the only option was to run the plate or buy a new piston and get it rebored. so i opted for the plate and nacs racing says they run it on all of theres with the 89 motor with the 86 piston with this plate . i would appreciate anyother opinions on this . thank you

 

The larger case volume can lower the primary compression ratio. But with an aftermarket exhaust and properly tuned, I've found that there isn't a noticable defecit in low end power(caused by the larger volume and less velocity). I've put together 3 motors recently, one was previously ported, and the other two were basically bolt-on's (pipe, carb, rad valve, thinner head gasket)and they all felt really sharp and good.

 

the quad has a prodesign coolhead with a 20 cc dome v-force reeds 39 carb paul turner midrange pipe the cylinder has been ported but no name of who did the porting and before i tore it apart compression was at 185 lbs i also run a k&n filter with a outerwear pre-filter

 

You will like runnning the spacer plate. It will give you some extra power. Also, by using the 86 piston you can go up to 14th over and not have to resleeve. Try it, you should like it.

 

Use the spacer.

 

First of all, you can't use a .140 over piston in an 89 engine. You can only use the .140 over piston in an 86 cylinder, so your point is worthless. The 89 cylinders(which is what the original person said they had) can only go to .080 over. Second, the spacer plate's theoretical function is to raise the crankcase volume and therefore double the volume available for fuel in the crankcase. It does lower the overall compression ratio, but with a ported engine that doesn't matter because they usually compensate for the plate. I have heard mixed opinions about the effectiveness of the plate. It has been about 50-50 on whether it actually serves any purpose, so I guess you will just have to try it and see. There is no way you will be able to tell any difference unless you use a dyno, that is how subtle it will be. If you do use a spacer plate, don't forget to get a long stud and dowel kit, otherwise you won't be able to bolt the cylinder down.

 

i did order the dowell kit also iam going to do this only because it is my best option right now to do in order to have it ready for this weekend .but next time I need to bore it i will decide weather to go with the 89 piston or keep the 86 with the plate.

 

Some small points for you to realize. The '86 piston's wrist pin boss is 5mm lower than the later models(hince the spacer plate). So it tends to be more Dome-heavy(top heavy). Now the skirt is raised, in comparison with the boss. It ALSO has a BIGGER cutout on the bottom for more intake duration. The less skirt area tends to create piston slap from wear sooner than the later style. My 2 cents is that Honda changed the design to promote better durability and longevity.

 

When you use the spacer plate on the 88-89 engine you must then use the 86 piston to get the piston to come to the top of the cylinder. This is because of the different location of the wrist pin, like the other person said. Yes the 88 only goes to 8th over, but by using the 86 it goes to 14th over. If you can not come up with the long studs, we were told then to turn out the stock studs 5 turns.

 

thanks for the replys i have decided to scrap the cylinder and start over with a new cylinder and piston and forget the spacer.this is my only options because my 89 cylinder was on its last bore and if i put in a new 89 piston i would have to rebore the cylinder again to match the new piston