Topic: DIY Egli Sohc 4

[mec]

hello to all,

no, i am not dead or gone

currently i am building an egli frame for a friend of mine. bike will be a dohc kawa 750 with some performance stuff inside the engine.
frame parameters will be the same as my sohc racer: wheelbase 1430mm, rake 23°60`, trail 90mm, prospective weight 160kg.

building process of the frame and swingarm is coming to an end, minor weldings (rear shock mounts,...) have to be done. frame and swingarm will be nickel plated.

some new tools help in the fabrication process:
i bought a cheap digital protractor. this tool helps to measure the various angles of the tubes joining each other. i can set my mill at these angles and do better cuts to have less gaps at the welding joints.

one more helper: a self leveling x-line laser. this device shows the correctness of the 90° angle of the steering head to the swing arm pivot. but in the end a plump line and a spirit level do have the last word.

mec

[SOHC4 Cafe Racer Fan]

Awesomeness! 

[Terry in Australia]

Beautiful work Mec, I had a poster of an Egli Kawasaki 900 above my bed as a teenager back in the 1970's, I'd love to own one! Cheers, Terry.

[voxonda]

Maybe you should make a serie, know I am interested........

[turboguzzi]

hei mec

looking fwd to see the result

does your friend stay as 750c.c. or big bores it? What class can he race it?

i weighted my very stock GPZ750 as 180 kg dry in the official scales at our last race, and its got the heavy stock frame, stock wheels, steel tank, etc. Very few weight reduction improvements, so i think 160-165 should be achievable.

how much did your SOHC Egli monster weight?

[mec]

hello TG,

from what i have heard my friend will big bore the engine, additional port job, cams, 29er smoothbores.

curious what the bike will weight.

my egli replika has 170kg dry. unfortunately the engine is on the heavy side with its old fashioned primary drive.

mec

[mec]

now the Z750 is in its final building stage, electric and fairing mounts have to be done.

mec

[mec]

cause there is some time left, some weeks ago i started building my monoracer: engine is a 4valve rotax, 560ccm, pretty standard tuning stage.

rolling chassis is build as near as possible to modern moto3 racers: similar wheelbase, similar rake and trail, similar overall dimensions. however 18" wheels and some more kilogramms.
wheels are tubeless from Kineo Wheels.
frame as usuall steel tubings, fork from an early cagiva mito, rear dampers wilbers.

seat and fairing from moto-forza, tank alu homemade.

titanium megaphon from 0,6mm sheetmetal, cant imagine it will withstand the vibrations

mec

[malcolmgb]

There was a Supermono Race series in the  UK about 2008/9 time, is it still going in Europe? Great racing on home built bikes, some using a Honda RS125 frame as a base.

[Terry in Australia]

Beautiful engineering as always Mec, I love that Rotax engined racer, that frame looks about as rigid as a frame could get! Cheers, Terry.

[Retro Rocket]

Beautiful engineering as always Mec, I love that Rotax engined racer, that frame looks about as rigid as a frame could get! Cheers, Terry.

Nearly as rigid as me just looking at it...

[Terry in Australia]

Beautiful engineering as always Mec, I love that Rotax engined racer, that frame looks about as rigid as a frame could get! Cheers, Terry.

Nearly as rigid as me just looking at it...

Thats a mental picture that another man shouldn't have! (not that there's anything wrong with it........)

[mec]

Beautiful engineering as always Mec, I love that Rotax engined racer, that frame looks about as rigid as a frame could get! Cheers, Terry.

Nearly as rigid as me just looking at it...

Thats a mental picture that another man shouldn't have! (not that there's anything wrong with it........)

 

@malcolmgb: yes, there is a supermono racing series in europe with 5 races (assen, schleiz, oschersleben, redbullring, most), see www.supermono.de


yesterday my rotax had its first run.
there are good and bad news: the best thing....the bikes weight is 99.5kg dry (including a heavy weight alternator which will be superseded by LiFe accus in the future). rear wheel hp 57hp at the moment.
bad news: the engine produces vibrations so that there is no chance to run it at high revs for more than a few seconds. the seat, handlebars hurt. furtherway i see no chance that the frame nor crankcase will hold for more than a few laps. it will take some weeks (?) till we find a solution. i am sure there is something wrong with the crankshaft or their balancing.

mec

p.s.: at full throttle you can see both in-valves 

[Syscrush]

Does that engine have any kind of counterbalancer?  What machine is it originally from?

Older KTM LC4 engines were singles with similar power output and used a steel trellis frame.  They vibrate to the point of being almost unbearable but they hold together OK.  You might want to look into how those bikes are put together.

I'm looking forward to seeing how this thing works once you have everything sorted out on it!

[turboguzzi]

looks very good mec (as always   )  are you planning to race it or just for fun?

[scottly]

99.5 Kg dry!!!! My '82 CR480R 2-stroke MX bike had an advertised dry weight of 103.18, and it had almost no flywheel at all! In fact, every year after that, the flywheel weight was increased to help smooth out power delivery to the rear wheel. What does the Rotax motor weigh? IIRC, a Honda XR500 motor is about 40 Kg.

[mec]

@syscrush:
i have seen this engine in various bikes: KTM Rotax, Aprilia, MZ, CCM. most of them have their roots in dirt racing. in fact the engine is from a KTM Rotax GS, see https://www.google.at/search?q=KTM+rotax+GS&safe=off&hl=de&tbm=isch&tbo=u&source=univ&sa=X&ei=QNCXUbXoGorZ4ASouYCwBQ&ved=0CC8QsAQ&biw=1311&bih=627

yes, the engine does have a counterbalancer, and from what i have heard it is not possible to mount the counterbalancer the wrong way (otherwise it comes in contact with the crankshaft).

@TG: its more or less just for fun. but there is a good chance that we will race it in the "Grabtheflag" series.

@scottly: weight of the engine is 44kg.


last thursday the bike had its first rollout at pannoniaring. the first laps i did with my friends ktm-rotax, a 560ccm single racer with 114kg. i wanted to get a feeling for the single cylinder vibrations. the bike had some vibrations, but all within comfortable limits. next turn i tested my new racer and was astonished that all the vibrations on the dyno felt much better on the track. it was very similar to my friends bike. i decided to do some laps and noticed that  the bike was more than willing to corner, however it was stable at high speed passages. next turns 4 of my friends did some laps and were very happy with its lightweight and cornering ability. 330mm front brake was disappointing, but things changed during the day. the new brake pads needed some brakin period and after this the front brake performed well.
front and rear suspension was on the stiff side. logical, the rear dampers are from my race guzzi.
the new lectron carb was on the lean side, especially in the low rpms there was a hesitating from the engine side. new needles are in order (as are rear dampers).

in one fast lefthand corner under hard accelerating i had a tankslapper. the steering damper was my friend and i am not sure what happened without it. at home i did some investigations: the bike has actually 70/20° rake and 75mm trail. no wonder that it loves corners (i wonder that it is stable at straight). i am sure that a adapted riding style (more weight at the front wheel) would cure this problem. in addition more negative front wheel travel would help also. more trail means new upper and lower triple clamps. better a flatter steering angle: fortunately i have the steering bearings in aluminium inserts. new inserts bored 2° inclined seems to be the way to go.
but first we will do some more test runs with better suspension, less tire pressure (avon 2.1bar).

stay tuned

mec

[Retro Rocket]

Wow, thats not much trail Mec, no wonder the bike was nervous , a steering damper would be a necessity ...
Beautiful bike....

[Syscrush]

last thursday the bike had its first rollout at pannoniaring. the first laps i did with my friends ktm-rotax, a 560ccm single racer with 114kg. i wanted to get a feeling for the single cylinder vibrations. the bike had some vibrations, but all within comfortable limits. next turn i tested my new racer and was astonished that all the vibrations on the dyno felt much better on the track. it was very similar to my friends bike.

GREAT!

That makes sense given that it's a counterbalanced motorcycle engine.

the new lectron carb was on the lean side, especially in the low rpms there was a hesitating from the engine side. new needles are in order (as are rear dampers).

I'm looking forward to hearing how you make out with that carb - I thought that they're really only good for WFO over a narrow RPM range.

in one fast lefthand corner under hard accelerating i had a tankslapper. the steering damper was my friend and i am not sure what happened without it. at home i did some investigations: the bike has actually 70/20° rake and 75mm trail. no wonder that it loves corners (i wonder that it is stable at straight). i am sure that a adapted riding style (more weight at the front wheel) would cure this problem. in addition more negative front wheel travel would help also. more trail means new upper and lower triple clamps. better a flatter steering angle: fortunately i have the steering bearings in aluminium inserts. new inserts bored 2° inclined seems to be the way to go.
but first we will do some more test runs with better suspension, less tire pressure (avon 2.1bar).

Glad to hear that it wasn't worse and that the damper saved your bacon.

stay tuned

COUNT ON IT!

[SOHC4 Cafe Racer Fan]

I love that tail. I wonder if anyone reproduces it.

[turboguzzi]

with 20 degs / 75 i am not that surprised it tank slapped, but the reason could be also guzzi shock with guzzi rates you sure have quick steering but also loose feel for what the front is doing

the dutch team i bought my XTZ660 motor from has moved this year to the newer four valve motor and after the first run had to change the balance factor because of hard vibrations. also a balance factor that works well with one frame stiffness/mass might not work with another. i hope not to have this problem with my XTZ/TZ racer...

[mec]

once I had lectrons on my cb900 semi works racer. they were usable through the complete rpm range. hoping that this will be the same on my rotax.

the tail is from http://www.motoforzafairings.com/de/category

TG: welcome in the Club of the mono vibrators


have been working on an adjustable cam wheel. unfortunately rotax does not have a comfortable solution for degreeing in your camshaft. much worse the camshaft belt is an oldfashioned design with flat tooth profile, nowadays rounded teeth are common use.
first try was a camwheel of five parts, the outer tooth profile matching the belt made on my cnc mill. drawings done by scanning the existing wheel. the inner toothing was made on my conventional mill after grinding a corresponding tool and using the mill as a shaper.
the inner toothing was perfect, the outer not so well. maybe the wheel is usable, but the teeth are not perfect. i think they will destroy the belt after some time running.
next step was grinding a rotating "one finger cutter" (fitting the teeth) and mill the outer toothing with help of a Rotary table. this worked best, the belt fits the wheel.
when this adjustable timing wheel will work, it will be a major improvement timing the cam. when it will fail, i will let you know

mec

[SOHC4 Cafe Racer Fan]

once I had lectrons on my cb900 semi works racer. they were usable through the complete rpm range. hoping that this will be the same on my rotax.

the tail is from http://www.motoforzafairings.com/de/category

TG: welcome in the Club of the mono vibrators


have been working on an adjustable cam wheel. unfortunately rotax does not have a comfortable solution for degreeing in your camshaft. much worse the camshaft belt is an oldfashioned design with flat tooth profile, nowadays rounded teeth are common use.
first try was a camwheel of five parts, the outer tooth profile matching the belt made on my cnc mill. drawings done by scanning the existing wheel. the inner toothing was made on my conventional mill after grinding a corresponding tool and using the mill as a shaper.
the inner toothing was perfect, the outer not so well. maybe the wheel is usable, but the teeth are not perfect. i think they will destroy the belt after some time running.
next step was grinding a rotating "one finger cutter" (fitting the teeth) and mill the outer toothing with help of a Rotary table. this worked best, the belt fits the wheel.
when this adjustable timing wheel will work, it will be a major improvement timing the cam. when it will fail, i will let you know

mec

Mec,
Can you be more specific as to the seat model? That site has so many different ones.

[mec]

once I had lectrons on my cb900 semi works racer. they were usable through the complete rpm range. hoping that this will be the same on my rotax.

the tail is from http://www.motoforzafairings.com/de/category

TG: welcome in the Club of the mono vibrators


have been working on an adjustable cam wheel. unfortunately rotax does not have a comfortable solution for degreeing in your camshaft. much worse the camshaft belt is an oldfashioned design with flat tooth profile, nowadays rounded teeth are common use.
first try was a camwheel of five parts, the outer tooth profile matching the belt made on my cnc mill. drawings done by scanning the existing wheel. the inner toothing was made on my conventional mill after grinding a corresponding tool and using the mill as a shaper.
the inner toothing was perfect, the outer not so well. maybe the wheel is usable, but the teeth are not perfect. i think they will destroy the belt after some time running.
next step was grinding a rotating "one finger cutter" (fitting the teeth) and mill the outer toothing with help of a Rotary table. this worked best, the belt fits the wheel.
when this adjustable timing wheel will work, it will be a major improvement timing the cam. when it will fail, i will let you know

mec

Mec,
Can you be more specific as to the seat model? That site has so many different ones.

yes, try this one: http://www.motoforzafairings.com/de/product/Yamaha-XS400/OYU-S_UNI-seat-Yamaha

mec

[SOHC4 Cafe Racer Fan]

once I had lectrons on my cb900 semi works racer. they were usable through the complete rpm range. hoping that this will be the same on my rotax.

the tail is from http://www.motoforzafairings.com/de/category

TG: welcome in the Club of the mono vibrators


have been working on an adjustable cam wheel. unfortunately rotax does not have a comfortable solution for degreeing in your camshaft. much worse the camshaft belt is an oldfashioned design with flat tooth profile, nowadays rounded teeth are common use.
first try was a camwheel of five parts, the outer tooth profile matching the belt made on my cnc mill. drawings done by scanning the existing wheel. the inner toothing was made on my conventional mill after grinding a corresponding tool and using the mill as a shaper.
the inner toothing was perfect, the outer not so well. maybe the wheel is usable, but the teeth are not perfect. i think they will destroy the belt after some time running.
next step was grinding a rotating "one finger cutter" (fitting the teeth) and mill the outer toothing with help of a Rotary table. this worked best, the belt fits the wheel.
when this adjustable timing wheel will work, it will be a major improvement timing the cam. when it will fail, i will let you know

mec

Mec,
Can you be more specific as to the seat model? That site has so many different ones.

yes, try this one: http://www.motoforzafairings.com/de/product/Yamaha-XS400/OYU-S_UNI-seat-Yamaha

mec

Thanks, Mec. It looks fantastic on your bike.