2X cams with 10.25-1 ?

I bought a 79 shaftie that has a 1045 kit and a 4-1 exhaust. The cranking compression is about 200 psi. Will a set of 2x cams reduce the cranking pressure to a reasonable amount? I am planning to use the stock airbox and not really looking for a performance increase, I just would like to make the bike more usable.
At this point, I have started the bike but have not tried to ride it, I assume the 200 psi will be a problem.... am I correct? The bike is a Canadian model with 28mm non pumper carbs- 15 pilot 105 main.
The PO told me that it sat for a few years and starts fine put won't rev up. I cleaned the carbs (not dirty at all) and all jets and passages, also set float height. With no airbox or exhaust on it does indeed start great and idles pretty well but just dies with any throttle. I am waiting for a new air filter to try with the airbox on (never had a filter in the box when I got it). It also will rev up to 6500 with full choke on and the engine warm. I have not been able to find the spec for the mixture screw for the Canadian model- its currently at 1 1/2 turns out.
Sorry to post engine and carb in the same location but wanted to give the whole story.

thank you for any help.
Don

Did you check the jet sizes. I would at least run 20/120 jets in that engine. That is a ball park guess but that engine won't rev with stock jets.

Roadflyer wrote: I bought a 79 shaftie that has a 1045 kit and a 4-1 exhaust. The cranking compression is about 200 psi. Will a set of 2x cams reduce the cranking pressure to a reasonable amount? I am planning to use the stock airbox and not really looking for a performance increase, I just would like to make the bike more usable.
At this point, I have started the bike but have not tried to ride it, I assume the 200 psi will be a problem.... am I correct? The bike is a Canadian model with 28mm non pumper carbs- 15 pilot 105 main.
The PO told me that it sat for a few years and starts fine put won't rev up. I cleaned the carbs (not dirty at all) and all jets and passages, also set float height. With no airbox or exhaust on it does indeed start great and idles pretty well but just dies with any throttle. I am waiting for a new air filter to try with the airbox on (never had a filter in the box when I got it). It also will rev up to 6500 with full choke on and the engine warm. I have not been able to find the spec for the mixture screw for the Canadian model- its currently at 1 1/2 turns out.
Sorry to post engine and carb in the same location but wanted to give the whole story.

thank you for any help.
Don

One problem is that compression gauges can't be 100% relied on for accuracy. I've seen 2 different gauges give 2 different numbers from the same cylinder.

All that aside, I ran 200 static PSI in my 1197 motor, on the street, with high test pump gas for over 5000 miles.

But to answer the question, cams with more duration than stock will lower the static pressure.

Larry C

The bike has 15/105 in it right now. You think it needs 2 sizes more on the pilot and 6 sizes more on the mains for pistons and a 4-1 with stock airbox? I never spoke with the PO just the guy who sold the bike for him to me. I have the reciepts from a shop that put the 1045 pistons and 4-1 into the bike back in 2008. i can't imagine that they did that work and sent him home with a bike that was not rideable at all. Maybe the airbox with a filter and the exhaust system back on the bike will make it run, even if poorly?? I will order up some jets. Do you think a 17.5/115 is a waste of time and $$?

Thank you for the help.

I know my compression tester reads a bit high, it actually read 210-210-230-210. The 230 is probably a loose valve clearance on #3. Do you think installing the 2X cams is worthwhile? or just pour the best pump gas I can find into it and jet a bit fat? What about carving static timing slots into the timing plate ( fixed electronic stock setup now) and tighter advance springs or lightening the advance weights?

Thank you for the info.
Don

17.5/117 will probably not do. It might with a stock air box. I have always run pods. You can try that. I would go what I suggested. Call Z1E the jets are cheap. Roy

I ran something similar to 20/120 on my Kz900 with 1075cc 10.25:1 Wiseco kit and pods on VM26's.

no point in worrying about cams yet. the only reason u would consider cams would be if u HAD to lower the compression. 200 psi on premium gas should be ok. i have 200psi with longer duration cams.
get the jetting worked out. if it pings after that, then u can look for ways to reduce the ping. more cam duration will help, dif timing curve would be another choice. i installed a dyna2000 with pre programmed curves. or retard timing.

With those jets in it the bikes not going to run very well without the airbox & filter. Id go with the 20/115 combo but it depends on your elevation too. Youll just have to see how it runs once you have all that done & go from there. Is that a points bike or electronic ignition? If it has points you might want to check the advance weights to see if they are free if its been setting

The bike is electronic ignition but uses the same sort of mechanical advance as the points setup. I've already been into that and its all cleaned and lubed. I'm only at 1110' elevation and the bike came from the coast so elevation correction is nil. I have a bunch of stuff coming from Z1 and will see if it runs at all with the exhaust/airbox/ filter installed.

20/120 sounds fine for pods, i'm going to be using a stock airbox though.

Roadflyer wrote: 20/120 sounds fine for pods, i'm going to be using a stock airbox though.

But not stock cams.
You are going to have to have a small jet to get you to at least 3500 RPM wheather it is 17.5 or 20. It will drive you nuts when the bike runs out of gas at that point. And on the big jet that is the RPM you will be doing a lot of riding and I will guarantee that again will drive you nuts.

We are all here to learn. Start where you think you should go and if you are right that is fine. I just have a drawer full of 17.5 jets that I have taken out of my bikes and others peoples bikes.