Support GPR Camp!!

Balancer or not?

Discuss technical information.
Post Reply
User avatar
grunbay
Posts: 17
Joined: Thu Oct 04, 2018 7:01 pm
Location: Southern Maine
x 5

Balancer or not?

Post by grunbay » Wed Mar 13, 2019 3:44 pm

I am building a Derbi race motor. I pulled the donor motor apart and have determined that the timing side is stepped with a woodruff key. I ordered a Malossi crank. They offer one with the tapered end and one with the stepped end. I purchased the one with a stepped end (Malossi #5312590). I have now pulled the motor apart and am preparing to reassemble it. However, I don't know whether the Malossi crank is balanced to run with or without the OEM internal balancer shaft. My motor is marked "SendaH".

I have asked Malossi, but am not receiving an answer. Does anyone know the answer to this question?
0 x

User avatar
toratora
Posts: 3161
Joined: Wed Oct 11, 2017 1:05 am
Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
Aprilia RS50
x 1768
x 1977
Contact:

Get the Balance Right (Yes I’m quoting the Mode)

Post by toratora » Wed Mar 13, 2019 6:39 pm

You want to run with a balancer. It makes the engine smoother. From what Remi discovered there are even custom balancers out there. I have a post on here somewhere about how to set things. I’ll see if I can find it and link it.

Yup here you go: How to balance a GPR Engine.
0 x

User avatar
kaldis12
Posts: 260
Joined: Tue Jul 31, 2018 3:04 pm
Location: Hungary
x 25
x 159

Re: Balancer or not?

Post by kaldis12 » Thu Mar 14, 2019 2:54 am

I think on a race engine it should be left out. I didnt put it in either, altough its a different engine. You sould balance the crankshaft out anyway before assembling it. If you put in the balancer you will lose a bit of a performance. On the street its not that important but on the track, it is very noticable.
If you want to race, balance the crankshaft and leave the balancer out
If you want to go on the streets, then put the balancer in.
0 x

User avatar
RemS
Posts: 59
Joined: Mon Feb 26, 2018 2:27 am
Location: FRANCE
x 32
x 88

Re: Balancer or not?

Post by RemS » Fri Mar 15, 2019 2:05 pm

Crankshaft Malossi RHQ référence, ONLY for €2 GPR motor With balancer:

5312590
Image

Crankshaft malossi RHQ référence, for derbi senda €2 :

5312320
Image

The better for a race engine is a derbi GPR engine ( whith balancer)

Caution!!! A balancer is not possible in derbi senda crankcases ( or whith machined )
0 x

User avatar
grunbay
Posts: 17
Joined: Thu Oct 04, 2018 7:01 pm
Location: Southern Maine
x 5

Re: Balancer or not?

Post by grunbay » Fri Mar 15, 2019 5:08 pm

Very interesting!

My motor (that I bought from a guy for $100) is Marked "Senda H", so it presumably came from a Senda. It has both a mechanical tach drive and an internal balancer shaft.

I'm gonna leave the balancer in and see how it runs on the dyno.

Thanks for taking the time to help me out!

See you at the track!
0 x

User avatar
RemS
Posts: 59
Joined: Mon Feb 26, 2018 2:27 am
Location: FRANCE
x 32
x 88

Re: Balancer or not?

Post by RemS » Sat Mar 16, 2019 3:41 pm

My mutiples crankcases GPR are notified « SENDA H »
0 x

Post Reply