Kit to make 422 into 428

[bullitt]

It appears I will be installing a 27 or 28 hp Koher into the 422 as posted ealier.

I am considering documenting the conversion and making it into a kit, using largely commercial parts at about $2k.

However, there is no point in doing this is there is not a market for it that will cover my costs and provide a small profit. To support that, I need some idea what the market for such a kit woud look like to help in negotiation with potential suppliers.

If this works out, I have some other ideas that could be of use to PT owners that might follow.

If you think you would be seriously intersted in the 422 to 428 conversion, please send me a private message so I can determine if it potential market is worth the investment of time.

thanks
bullitt

 

[bullitt]

It seemed like a good idea at the time, but it is impractical.

The Robin crankshaft is not centered side to side and the crankshaft is .87" lower than the kohler, therefore extensive modification to the cradle is required, meaning its reuse is impractical.

That means the conversion is not practical independant of parts from Tazewell, and so dies the dream of a cheap upgrade to more power.

I will still be putting the largest engine in that the Kohler cradle I will have to buy will support, and will provide that info to anyone who is interested.

bullitt

 

[bubenberg]

if you ever try the conversion to a diesel eng. i would be interested. one engine that comes to mind is the Cummins diesel eng. i think it was last year we toyed around with this conversion on this site (about 18 hp)

looking forward to hear from you, keep the thinking juices going. /forums/images/graemlins/smile.gif

 

[MossRoad]

Maybe one of these? /forums/images/graemlins/laugh.gif

 

[bubenberg]

what do you think? have you checked out the dimension Mr. M.R.? reads quite like what i would like, the <font color="green"> "green beasty tank" </font>will outlast the Kohler eng. by many years even under my more intense use and just like you i LIKE my pt425 and am going to give it(really me ) more toys to play with. My goal is that the 425 is going to make me the money to get a 1845. /forums/images/graemlins/blush.gif /forums/images/graemlins/smile.gif /forums/images/graemlins/cool.gif /forums/images/graemlins/tongue.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/confused.gif /forums/images/graemlins/grin.gif

hans

 

[MossRoad]

No, I haven't checked it out... I was just enticing everyone else to check it out for me /forums/images/graemlins/grin.gif

 

[bullitt]

As always, the devil is in the details.

The limiting dimension in my view is length. This is the reason I ruled out the 28 hp Kohler engine yesterday. It is possible to make it fit, but you will not be able to remove the rear pump without pulling the engine and disconnecting the hydraulic hoses because it is an inch longer. This is a bigger problem to me than the difference in hp and torque.

At this point, unless a new possibility opens up, it looks like will will be putting in the 25 hp kohler that is in the 425. Once I get that model numbers, I will get the drawings and check out some of the more exotic angines.

bullit

 

[duane]

Bullit,

Ed went through a incline climbing problem with his PT425 while powering his 60" mower. In his case, it was'nt a motor horsepower issue, but a system relief lifting in his transmission pump due to the wheel torque required. The only reason I mention this is I would not want to see you go through all this effort and expense, to find out that you are limited by the hydraulic transmission. Another solution to more wheel torque (incline climbing ability) is to go with smaller diameter tires, or different wheel motors. I'm guessing that new wheels and tires would be about $400 while new wheel motors $700 - $1000. In either case, you would lose travel speed on the top. This might not be acceptable to you. No matter what option you pick, keep up the ingenuity and vision. Let us know how we can help.

Duane

 

[Pacesetter300]

Another possibility that hasn't been mentioned. I see Northern Tools has 24HP V-twin Honda GC series engines for about $1200. I would say it's worth looking into. Out of curiosity, I looked at the specs on the Robin. The net HP is 18 and they only promise 85% of that, so it could be as low as 15.3 On top of that you're off approx 5% for every 1/4 mi in altitude. Heck, someone in Denver could have about 12 1/2 Hp net, almost 10 less than advertised!
Pacesetter

 

[MossRoad]

</font><font color="blue" class="small">( Once I get that model numbers )</font>

Ok, Ok /forums/images/graemlins/laugh.gif

I was busy yesterday, as my 10 year old was testing for her green belt in Karate... she passed with flying colors /forums/images/graemlins/smile.gif

Here's the numbers from my PT425 Kohler:

MODEL CH25S
SPEC # 68500
FAMILY YKHX5.7252GC

Hope this helps.

FYI. It was 5 degrees in the shed this morning and the ink froze in the pen /forums/images/graemlins/shocked.gif

And I'm supposed to go inner tubing or cross country skiing today..... BRRrrrr. /forums/images/graemlins/tongue.gif