Gen 1 - low compression - build questions

[JaiHutcherson]

Hey All,
I posted here with great results including my compression test questions that lead me to today.

2007 busa 4-1 alien head exhaust, pair valve removed and ecu flash from smitz racing. Other than that all stock.

I’m getting 169 on two cylinders and 172 on the other two when doing compression test. I have not performed a leak down test as of yet or checked valves. I’m ready to just do a rebuild and check/fix valves as I go. I would like to do the 1397 kit from APE racing. It comes with block, pistons and rings. I am assuming I’ll need to get some head work done for the ladder bore.... what does that entail? Will there be anything else I will need with this kit?

I’m not trying to race or be the fastest in the street. 195-200mph I get now.... or was getting last summer before started losing compression..... is plenty for me. I’d like to feel a bit more torque and it pull a bit harder. It’s the reason I’m thinking do the 1397 now while it’s all apart anyway.

I’ve not rebuilt a busa but I do all my own maintenance. And feel I can handle the project. I’m looking to the experienced guys on here to help me buy what is needed, no what is advertised, and get my bike back up to the power I had before. Any and all help is much appreciated and welcomed as well as corrections in my thinking. Just want to do it right the first time and get her back!

thanks
Jai

 

[michael parris heuberger]

Hey All,
I posted here with great results including my compression test questions that lead me to today.

2007 busa 4-1 alien head exhaust, pair valve removed and ecu flash from smitz racing. Other than that all stock.

I’m getting 169 on two cylinders and 172 on the other two when doing compression test. I have not performed a leak down test as of yet or checked valves. I’m ready to just do a rebuild and check/fix valves as I go. I would like to do the 1397 kit from APE racing. It comes with block, pistons and rings. I am assuming I’ll need to get some head work done for the ladder bore.... what does that entail? Will there be anything else I will need with this kit?

I’m not trying to race or be the fastest in the street. 195-200mph I get now.... or was getting last summer before started losing compression..... is plenty for me. I’d like to feel a bit more torque and it pull a bit harder. It’s the reason I’m thinking do the 1397 now while it’s all apart anyway.

I’ve not rebuilt a busa but I do all my own maintenance. And feel I can handle the project. I’m looking to the experienced guys on here to help me buy what is needed, no what is advertised, and get my bike back up to the power I had before. Any and all help is much appreciated and welcomed as well as corrections in my thinking. Just want to do it right the first time and get her back!

thanks
Jai

Hi. First off how are you doing the test? 1st hold the throttle wide open, the battery must be fully charged and stay that way. Than do a 2nd test, but this time put a little oil in the spark plug hole If it goes up it could be bad rings. the do a leak down test. If you co not know how just read up about it.

 

[busakiller]

If it’s stock that’s pretty close to where they can test at. I have a stock motor and it’s at 180 psi. So your not far off and could be just the gauge. My 1397 reads over 280 psi per hole

 

[JaiHutcherson]

Hi. First off how are you doing the test? 1st hold the throttle wide open, the battery must be fully charged and stay that way. Than do a 2nd test, but this time put a little oil in the spark plug hole If it goes up it could be bad rings. the do a leak down test. If you co not know how just read up about it.

I did not add oil for a second test. The other techniques learned here. I did do about three tests just to see if I got the same results. I’ll try the oil tonight. Thanks you.

 

[JaiHutcherson]

Hi. First off how are you doing the test? 1st hold the throttle wide open, the battery must be fully charged and stay that way. Than do a 2nd test, but this time put a little oil in the spark plug hole If it goes up it could be bad rings. the do a leak down test. If you co not know how just read up about it.

Ok,
Pulled it apart and did compression test then added tspoon oil and retested. I could not get my hands on leak down test kit it on way from Amazon sat. Delivery. In mean time here are results:

#1
169
171 w/oil added

#2
171
182 w/oil added

#3
171
182 w/oil added

#4
169
172 w/oil added

so, I was moving bike to get more light and noticed a crap load of oil on the ground... fresh clean oil. I looked under tank again and confirmed I didn’t spill any while putting in spark plug holes. Here are some pics. Looks like coming from a small (1/8 inch) that’s under each exhaust out. Is this correct since I put in cylinder or is this an issue???? Pics are as good as I could get. Thanks for your input and directions.

 

[Berlin Germany]

1. standard pressure at the gen1 is 171 - 228 psi - see gen1 manual, page 2-31
2. if the pressures of all the 4 cyl. are more or less as "equal" as you wrote it seems to be ok - in my view 3-5 psi (~0.2-0.3 bar) difference is quite nothing - normal tolerance
- whenever you meassure never forget to give 100% full throttle - what can´t breath that can´t compress !
3. control all the valve clearances and move em all, if at the middle or smaller, near/close to max like EX 30/100mm , IN 20/100 mm and do the compr. test again.

4. and what i would do also is the pressure leaking test (with around 5 bar/72psi) too - it tells you a lot about the state of piston-cyl. clearance, piston rings and the valves.

 

[Bigboy Busa2]

Seen this today. Thought it was relevant

 

[Berlin Germany]

@Bigboy Busa2

the lh box looks nice and useful for all sizes of spark threads
the rh laptop no one needs for compr. tests - in the end, I would even find it a rip off

 

[Bigboy Busa2]

@Bigboy Busa2

the lh box looks nice and useful for all sizes of spark threads
the rh laptop no one needs for compr. tests - in the end, I would even find it a rip off

I understand. I consider it more of a quick tool to narrow down problem. I was hoping more of $200 range. But you would still do a compression test in the end. But I found it interesting

 

[JaiHutcherson]

Circling back around to my post:

I did a leak down test. 1 and 2 I could hear in throttle body with a 22% leak. 3 and 4 not in throttle body but definitely in the crank case through the oil fill hole. I’ve pulled the throttle body looked down the intake and here are some pics. Before I even try to get the valve clearances wanted to find out if the valves should look like this. If not, no point in clearances. I’ll pull the motor, do the 1397 bore and find someone to rebuild the head/valves. Thanks for any and all input.

 

[michael parris heuberger]

Circling back around to my post:

I did a leak down test. 1 and 2 I could hear in throttle body with a 22% leak. 3 and 4 not in throttle body but definitely in the crank case through the oil fill hole. I’ve pulled the throttle body looked down the intake and here are some pics. Before I even try to get the valve clearances wanted to find out if the valves should look like this. If not, no point in clearances. I’ll pull the motor, do the 1397 bore and find someone to rebuild the head/valves. Thanks for any and all input.

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Hi. What do you want from the bike? More HP? If the bike was mine I would keep it stock bore? Do the valves put in low compression pistons and a stage 1 or stage 2 turbo. I would call Boosted Cycle Performance in Huston talk to Rob at # 630-807-9002/

 

[JaiHutcherson]

Lol. I want more hp/torque; not so much for speed. I raced motor cross for many years a lifetime ago and I can still feel the torque and quickness. I’ve had it tuned and new exhaust pair valve removed and air box. I was actually cool with that set up and my 45 rear sprocket. All that said to say.... I’ve never touched the cams valves or pistons because I simply do not know enough to make reliable decisions. Your post is refreshing. I actually do not even know what is involved in doing what you said. Do I need to get the cylinder honed? I did a valve adjustment today they were all out but doing it one line at a time out of the manual. Where I sit now is two pistons leaking about 22% in crank case valves no longer leaking. It’s time to either put back together and right it out til pistons too bad or make the move to new pistons rings and maybe get the head done.... anything at all would be very welcomed.

 

[michael parris heuberger]

Lol. I want more hp/torque; not so much for speed. I raced motor cross for many years a lifetime ago and I can still feel the torque and quickness. I’ve had it tuned and new exhaust pair valve removed and air box. I was actually cool with that set up and my 45 rear sprocket. All that said to say.... I’ve never touched the cams valves or pistons because I simply do not know enough to make reliable decisions. Your post is refreshing. I actually do not even know what is involved in doing what you said. Do I need to get the cylinder honed? I did a valve adjustment today they were all out but doing it one line at a time out of the manual. Where I sit now is two pistons leaking about 22% in crank case valves no longer leaking. It’s time to either put back together and right it out til pistons too bad or make the move to new pistons rings and maybe get the head done.... anything at all would be very welcomed.

Hi That is why I said to call Rob at boosted cycles # 630-807-9002. The 1397 tend to run hot.

 

[Boosted Cycle Perf]

The oil you see is coming from the drain holes in the spark plug bores. That’s normal if you don’t get oil directly in the spark plug hole.

 

[JaiHutcherson]

Hi That is why I said to call Rob at boosted cycles # 630-807-9002. The 1397 tend to run hot.

Will do today!

 

[JaiHutcherson]

The oil you see is coming from the drain holes in the spark plug bores. That’s normal if you don’t get oil directly in the spark plug hole.

Thank you!

 

[rubbersidedown]

It's all about choices Jai'
Pick one right. There are many factors to consider. For me,I love the HP that a turbo delivers,but to build it right is pricey. The gains from a big bore kit are OK,but not worth the $ in my opinion. If you are not going to race,I tell everybody to go for reliablity. Isn't that whats most important.A bike that starts,runs well and lasts for years.I think the Busa is one of the most bullet-proof motors of all time...till ya start to mess with it.
Back 20 years ago when everybody was doing this mod and that,chashing 5 and 10 horsepower,it sometimes came with issues.
If a perfectly running bike is important to you,re-build it bone stock.If you want to chase the ponies,get out your wallet and go for it.The "all motor" guys can steer you in the right direction from their trial/error or there's the turbo route.
You said it yourself,yer happy with the snap provided by a gearing change.
If down time and cash flow are a non issue for you,build the biggest baddest turbo or super charged monster ever seen.The top builders will gladly take your money.
Rubb.

 

[JaiHutcherson]

I hear you on all that! I’m working it all now. See which way is best and what is needed. I’ve torn down to pistons now. Have not inspected past head. Not seeing much wrong in valves. They were all within spec.... but I was hearing air (snap crackle pop) through throttle bodies so assuming seats/springs/??. I know I’ve had a pretty big power loss for about 2 months.... and honestly no clue where to look now. Starting the trouble shooting in the manual and looking for a reasonable head/cylinder shop. Trying to justify the 1397 but the more I dig the more I’m getting steered away. And yes, reliable, get on and feel the original power I got from slight mods maybe the answer. Lol I’ll know by tomorrow as that’s all the time I’ve given myself to pick.
Thanks for all the input

 

[rubbersidedown]

Any symptoms come with the power loss? Certain RPM? All the way thru the range? Feel like power was falling off?
Rubb.

 

[JaiHutcherson]

The best way I can describe is that it used to lift the front end 1-4 with just less than full throttle. I don’t feel like I better hang on 1-3 anymore. However, once RPM is above 5ish6k it feels like all the power is back. In 5th gear doing 100 I used to twist the throttle and still get that “hang on” sensation. Now, I get a slow ramp up to 140ish but once there, again, RPM’s up at that speed in 5th.... and suddenly I have power. Now, in that slow ramp up, if I drop throttle and then twist it back up it instantly gets that power feeling. I have not lost speed at all. I’ve lost the ability to get up to speed quickly..... which where it’s all at for me. If/when I figure this out, the build I want to do will give me just that; more quickness, torque, and power from 0 to 120. Top speed.... I’m real good with where it’s at for now.

and thanks for engaging.