Weed eater engine conversion

Heys guys, just joined the forum because I was looking for info on building a motor myself. Was wondering where you might have found these equations to come up with these results? Any input would be appreciated!
-Fishkilla

 

the above does not make sense to me ...for 1000 rpm and 1inch pitch you get approx 1 mph ...so this 7000 rpm and 1.92 pitch gives about 14 mph .....or we have 66% slip .....and we keep that slip as the size/pitch goes up or it will be doing 14 mph I dont think ....

I had an interesting e mail exchange with youngs props whilst looking for a prop for my longtail 6.5hp 2:11 www.youngprops.com .....this must be the only company that sells props and carnt tell you the pitch " steep near the boss tapering to zero at the tip "...and a metric hole ....now come on dont even go there ....

 

There is a place in south Louisiana that makes props. They make small brass & stainless pops for 5HP long tails. When I get back to Louisiana on Monday I will look up the number for you.

 

Can you share

Can you share the source of props you mention above. Many of us would liek to knwo.

Thanks -

Mark

 

Chrsegu has not contacted me by PM or otherwise...yes props is a problem which is why my right hand rotation unit chain drive was built ( almost finished just painting it = will post here ) Having much experience with props on outboards I know that you can do nothing without a rev counter ..hence all this talk of 1/3 throttle and the prop bogging ...this is the device I use ..runs to 25000 rpm 1 ,2,4 stroke ..one wire to wrap on the plug lead ..

ADDED 20/2/09 or 2/20/09 as you prefer.

This tacho is a unique design being ok on 1 stroke 2 stroke or 4 stroke motors . It has 5 8mm digits and runs to over 25,000 rpm It is availabe in the USA by contacting jimspring@verizon.net or in Australia contact noosapropshop@yahoo.com.au .

 

pistnbroke,

What is the make, model and source for that tach/hour meter?

 

This type of tach/hour meter is used a lot by go cart racers . They should be readily available through local cart racing supply outlets. My grandsons cart has one.

 

Well not quite john ..these meters are unique in that they will do 1 stroke 2 stroke and 4 stroke and have a large 8mm display of 5 digits and run to over 25000 rpm.

they are available from jimspring@verizon.net in the USA or by contacting noosapropshop@yahoo.com.au in AUSTRALIA .

 

Pistnbroke; You are correct, the unit you reference is much more sophisticated than a cart tach. My unit is a Mychron 4 single wire . It will handle 2 stroke or 4 stroke. It is digital and will display RPM , cyl head temp. interval times, and act as a data logger. I gave $150 used for mine.

 

Wow thats a lot on money ...these are $31 in the USA + postage and $65 In australia inc Express Post $60 each for two or more still with the express post ( Australian dollar worth about 35% less than the american )

 

www.northerntool.com item# 160590 @ $39.99 is very similar to pistnbroke's tach/hour meter. It has a non-replaceable battery that they say will last for 5 years.
Pistnbroke, is the paint dry on your longtail dry yet ? Looking forward to seeing it.

 

Pistnbroke/Kingfisher; Wish I had known about the models you guys reference. I could have saved a lot of money. The Mychron 4 is a bit expensive, it runs about $350 new. Thanks for the info.

 

Kingfishfer ..not quite the same ..does not do a 1 stroke engine ( 2 cyl 2 stroke and 4 cyl 2 strokes) Battery on the one I suggested is 10 years not 5.
dont see any buttons

 

doesn't it just measure off of 1 plug wire? In that case it doesn't matter how many cylinders it has. It just needs to know if it's 1 spark per rev or 2 revs per spark.

 

Not Quite Srimes

A one stroke fires at the end of each stroke ie twice per rev..two cyl 2 strokes do this with a double ended igniton coil.

A two stroke fires once per revoluton

A four strokes fires once per 2 revolutons thought most modern 4 strokes fire every revolution its called wasted spark ... most cars and Briggs and Stratton Honda ect