KZ650 Bonneville Bike Part 2

Two months after the Hot Bike issue (Feb 77).......Motorcyclist Mag (April 77) talked to Denco about building "The Worlds fastest KZ650" .... in it they talked about the Bonnie bike and here is most of it.

They said since the 141 mph record was a number of changes have been made.......For one they discovered that the 11 3/4 comp used was to high and have since lowered it to 10 3/4 to 1 on all there piston sets, Also that they discovered a few bent valves and have since deepened the valve pockets ..... they also discovered that the 31mm Keihins they were running (Although the article showed them running 29mm smooth bores) were to much carb and recommend the 29mm smoothes as the hot set up.

Dennis says knowing what he knows now and with the changes he said a full 10 mile per hour higher could have been added making it 151mph!!!

In the article they built a 706cc motor, 10 3/4 to one, A degree'd in KR150.420 lift cam (no other specs givin), 29mm SB W/ 50mm velocity stacks, Their ported and polished heads with stock valves, seals and their springs, (flowing 84 cfm) (stock Z1 head they said flows 82, no specs on the stock 650 head), stock cir clips (not teflon buttons) 4380 crome moly pins, HD clutch springs, a Torrington bearing clutch pusher (a must) and stock plates, A Gerex CDI ignition that he swears by, stock lower end, stock cam chain, timing advanced 2 degrees, Their header, Champion N2GYs (N59Gs for racing), A 15T front sprocket and stock HP Z1 valve lifters that were drilled like the RC ones I saw on here. The lifters were mainly were for ease of adjustment and he is working on HD shim unders that will hold up to the 420 lift. No shims were ever spit out though even though the Bonnie bike often saw 13,000 rs.

Although Motorcyclist said it might be a little high ......They (Denco) estimated 103HP at the crank and 90 at the wheel and set the IDBA E modified record at 11.23 at 116 and had since lowered it to 10.73 at 119 with this set up. Motorcyclist turned a 11.8 with it with the stock tire and granny shifting. Why they didn't do a slick and wheelie bar I have no idea...... All that rode the bike said that it was a animal from 7,000 to 11,000 rpm and since it needed to idle at 1,500 to keep it clean and was a little lacking down low...... would still run amazing and be more street able with their KR100 .....352 lift cam.

They also talked of the piston dome having a power notch design that burns cleaner and has better combustion (designed by Dennis and made for them by MTC ) Dennis claimed a 26 HP pick up with these over the stock Z! 900 pistons but didn't go any farther. No info on the 650 increase. Might be a little hype but wanted to report it. At this timethey were selling 695cc pistons, 706cc special order and the 738cc pistons that needed bigger sleeves..... all 10 3/4 only.

Also talked of putting a hollow tube where the oval o ring is on the cylinder (oil passage hole) to keep the o ring in place and leak free. Think the 78s on up solved that.

Dennis said 3 things you can do to a stock 650 to lower the 13.1 et to 12.7 is Put in Premium gas, advance the timing 2 degree's and install thin wired Champion N2G plugs although I did N3G as stock ones call for 4s so these are very cold. I'm sure I didn't see this big of an improvement but it ran crisp and very good. I'm sure I saw this in another article him saying this and adding a 15t front sprocket too but it didn't say this here...... He also said after this on a stock motor do the header ..... then the 29mm smooth bores as the hot set up..... then the bore and cam together.

Well anyway hope you liked the info and hope it was ok to put this under the engine section..... figured more folks would see it.......... if you are a s big a fan of the Bonnie bike and article as I am it would probably be worth it picking this issue up....... have never seen it printed out any where. ..... picked up a little info that wasn't in the Bonnie article...... God I wish Denco was still around ..... imagine what they would be running now. :woohoo:

Another article here with lots of pics.
www.google.com/url?sa=t&rct=j&q=&esrc=s&...XEEWq6CRjHXhsI06b5tg
Pete

pete greek1 wrote: Another article here with lots of pics.
www.google.com/url?sa=t&rct=j&q=&esrc=s&...XEEWq6CRjHXhsI06b5tg
Pete

I remember that article back in the day. One of MANY Kaw articles all throughout those years. Love the denco headers too. They were a top performance booster for 900/1000's also, although not as popular due to their shorter design and low visibility because of the left side exit. I wish I could find one now for one of my current projects. Thanks for the post Pete. Always up for a good reminisce of the bygone good old days of yore!.................................Mike
Vroom-vroom!!!

As soon as my warranty expired on my brand new 77' KZ1000... off came the stock pipes and carbs,
Then on went the Denco 4 into 1 pipes and re-jetted-re-needled carbs, as per what Denco actually told me to try, and it was NOT radical either.
Then also put a 35/15 sprocket combo on.
I had no trouble getting my KZ1000 with stock tires into the high (very high) 11's back in Detroit.
Of course I was in my late 20's and only weighed in at 132lbs back then! LOL
11.68 et was the fasted i ever got that thing.... maybe a fluke but it would run all day at the strip in the very low 12's and I'd ride it there and back home with my girl friend on the back and 43-45mpg.
Those were the days.... and I still have the bike with the same Denco headers and carbs,,, now a 1075cc Wiseco kit, stock carbs same 35/15 sprocket setup.

When I tell people I bought the bike new in 75 I get the ole fish eye. :lol: They just don't get it. :dry:
Steve

Thanks Pete will show folks the article I'm following up on..... Glad you kept the 1000 Mission and the header..... more than a few would kill for it.... sounds like you know how to ride it and have surprised a few people over the years...... In 73 I had a new 750 Honda a new 250 dirt bike and a lot of hope ..... In 74 I traded the Honda for a big block Chevelle later on that year wrapped it around a pole and got married.

I will admit the marrage worked out and still is but it put a damper on my toys...... stuck with dirt bikes till the winter of 80 when I gave up on getting the cash for a new liter bike and bought the slightly used 650 ..... had it ever since and really can't complain about how things worked out. Didn't really learn much about Denco till much later when I saw the Bonneville bike article (mid 90s?) ...... thinking things would have been much different if I would have .... was more of a big RC/ Vance and Hines, APE and Yosh fan back then.

I haven't actually seen or heard a Denco header on a 4 cylinder bike, It was all the 2 strokers that had the Denco expansion chambers, that made them sound soooo mean
& I, like almost all of my friends , took of the stock pipes & got a header on there, they all had Kerkers, V/H, RC, Yosh etc. I got me a Bassani which I loved, & had it on the bike until 2010 when the chrome started to peel off on the bottom & started to get rust pinholes, I sold it to a member here & he had the holes repaired & had it ceramic coated, I should've done that , SMH,


Bruce, do you have a pic. of the Denco on your bike
Pete

I'm not far off their number's no bar, street tire and stock cams.

zukdave wrote: I'm not far off their number's no bar, street tire and stock cams.

What's your best # to date, Dave? What cc are you running now?

Motor's 810 cc. the spec's are in my sig.
Our track is 1/8th. mile so no 1/4 mile time's yet
but has gone 7.34@98.73 with a 1.61 60ft. 1/8th mile.