103+ Compression

[fbn ent]

I get 165# on both cylinders in my '02 RG. 103", running the SE 103+ heads and Stroker piston kit along with a set of 103 flywheels. 10.5 ratio. I'm wondering what I should be getting. I haven't done a leakdown. I would rather not tear it down this year. Thanks.

[Hossamania]

What makes you think it needs a teardown?
Carb or efi? Throttle wide open during test?

[fbn ent]

What makes you think it needs a teardown?
Carb or efi? Throttle wide open during test?

Oops! EFI. Yes, wide open. Cranked with a button off the starter. No Easy starts. Just my OCD kicking in. I did notice the rear head is starting to need seals...

It doesn't use an out of line amount of oil but there are around 37K miles on it and I noticed a bit of a drop in performance last year. I can live it. I'd rather gather parts and do it next Winter though.

[fbn ent]

I didn't pay a whole lot of attention, kept no paper and didn't take a test when it was broken in.... Note to self: Keep good records when you want to keep a bike.

[kd]

You say 103+ heads.  What year are they and do you have ACR's?  If so, were they disabled for the test?  I am assuming by easy starts you mean cam and not ACR's.

They are nice and even which is good.  Seals won't drop compression.

[Hossamania]

What makes you think it needs a teardown?
Carb or efi? Throttle wide open during test?

Oops! EFI. Yes, wide open. Cranked with a button off the starter. No Easy starts. Just my OCD kicking in. I did notice the rear head is starting to need seals...

It doesn't use an out of line amount of oil but there are around 37K miles on it and I noticed a bit of a drop in performance last year. I can live it. I'd rather gather parts and do it next Winter though.

37k isn't a lot of miles, you can definitely keep riding it until you have all your parts and money collected for a rebuild.
A leak down test will help figure out if there really is an issue.
Did you dyno tune it? Another run might help show if there is a significant drop in power.

[FXDBI]

     What camshafts?  Bob

[fbn ent]

Hoss, no, I'm running a T-Max. Tweeked the timing a bit and let 'er rip.

Bob, Andrews 57 rings a bell but haven't tried to find my records yet. I may have something.

 

[Ohio HD]

I'd be more interested with just running the leak down test. If your not dropping down much during the test, I'd wait till later to work on it.

0% to 10% loss is a normal motor with some miles in it.
11% to 20% loss is a motor that's a little worn, but not ready to just strip it down yet.
21% to 30% loss, there's some major engine issues starting to deteriorate performance and maybe reliability.

[kd]

Still no answer on the ACR question.  Most 103 heads have them.  The compression is equal and that's good.  The 165# is right around some members have reported with ACR's activated.  Any chance of trying another compression gauge for comparison and using a car jumper battery to make sure of the cranking speed?  How many bumps before stopping and had the gauge stopped climbing?  Lots to be answered still.

[Ohio HD]

Agree, but without knowing how many cc's the heads actually are, the piston dome or no dome, head gasket thickness, pistons down the hole or not. As well knowing for sure if it's an Andrews 57 set of cams. That's why I said I was looking at leak down numbers for an idea of the motor health.

My best guess (    ) is the compression should be around 180 ish.

[kd]

Agree, but without knowing how many cc's the heads actually are, the piston dome or no dome, head gasket thickness, pistons down the hole or not. As well knowing for sure if it's an Andrews 57 set of cams. That's why I said I was looking at leak down numbers for an idea of the motor health.

My best guess (    ) is the compression should be around 180 ish.

I agree there's lots to know first.  I also would suggest no wet test until after confirming the previous test and after a dry leak down is done.  No point in contaminating and masking the ring seal with oil too soon.  It may just be the gauge or cranking speed. 

The perceived loss of power may just be getting used to it.  I know that's happened to me so I just hopped it up more. LOL

[rigidthumper]

2002 RG with the 103 probably would have been built with the 103+ heads (advertised 98CC, no ACRs) and the 22483-04 SE pistons (advertised +18cc dome). Most 40s close cams would put CCP close to 200#.

If they used a flat top piston, CR is 8.8:1, and those same cams would put CCP closer to 160ish.

[fbn ent]

Still no answer on the ACR question.  Most 103 heads have them.  The compression is equal and that's good.  The 165# is right around some members have reported with ACR's activated.  Any chance of trying another compression gauge for comparison and using a car jumper battery to make sure of the cranking speed?  How many bumps before stopping and had the gauge stopped climbing?  Lots to be answered still.

Sorry kd, I have manual ACRs. Heads are an 03 suffix maybe 04 to match the pistons. I sent them to Don D to clean them up and install bronze guides. It is cranking fine but I'll try the battery thing. IIRC, I got around the same the last (and only) time I checked all my bikes. Pressure went to 90 (ish) on first rotation. Turned it for seven cycles. Three runs each hole. I'll see if I can dig up another guage for S&Gs.

Ohio, yeah, I know I'm pretty light on info. As I get older, it is harder to keep my head in the game. I should have run a baseline comp test when I put it together. Will run a leakdown and see if I can find the cam info to verify. Bike still gets up and goes, maybe your right.

RT, that is the set up. I found the piston sheet after the original post was up. 200#? Crap!

[fbn ent]

I emailed Don D yesterday. I should have opened it first...

"On the 103+  head build 2011
100.6cc heads
20.5cc dome
10.5:1"

[fbn ent]

Leak down test was WAY high....coming apart now. Just happen to have a set of those pistons sitting on the shelf for just such an occasion.

[smoserx1]

What is your elevation above sea level?  It does make a difference.

[fbn ent]

3250'