Tuning is no problem but the original piston and rings are not very good for other than a mild tune. MB Developments recommend converting to GP standard or race type crankshafts then upgrade bearings and convert to a GP electronic ignition.
There are a number of cylinder conversions available.
Tuning is no problem but the original piston and rings are not very good for other than a mild tune.
MB Developments recommend converting the crankshaft to a race type and convert to electronic ignitions.
There are a number of cylinder conversions available.
A 200 cylinders using Vertex, Asso, Borgo, Hepolite or Mahle 3 ring pistons.
(MBD donít recommend any other makes unless itís the last resort).
PROS: good pistons in standard form with a large number of over sizes 66 to 68.6mm. Ideal for stage 2, 3 and 4 tunes, (could be used for mild stage 5 tunes) Quality cheap pistons which makes for a cheap conversion. No cylinder machining is required. Fits onto standard or race type crankshafts.
CONS: These pistons use the standard cast iron type rings which are prone to break with wide exhaust ports or high mileage worn cylinders.
B 200 cylinders using Vertex or Asso 2 ring pistons.
PROS: These pistons are an improvement over the original 3-ring type, piston quality is the same but the rings are improved. The rings are higher wearing with less chance of ring breakage. These pistons come with a large number of over sizes 66 to 67.4mm for Vertex and Asso pistons.
Although Vertex, Asso and SR pistons are creeping up in price they are to be considered cheap pistons compared to Japanese pistons.
These pistons are ideal for Stage 2, 3, 4 or 5 tunes. No cylinder machining is required. Fits onto standard or race type crankshafts.
CONS: The Vertex, Asso pistons have 3mm removed from the inlet port side this then increases the inlet port timing which doesnít always make for an improvement especially on standard engines or cylinders previously tuned for the standard skirt length pistons. (Some of the latest 2001 spec Asso pistons come with a full skirt at last!)
C 200 cylinders bored to 225cc using Vertex or Asso two ring pistons.
PROS: The rings are higher wearing with less chance of ring breakage compared to the inferior GPM and Meteor pistons. Vertex, Asso and SRP pistons although are creeping up in price are to be considered cheap pistons compared to Japanese pistons. No cylinder machining is required. Fits onto standard or race type crankshafts.
CONS: Only a small number of over sizes are available 70 to 70.8mm. On the last over size piston the cylinder bore gets a little thin. The Vertex and Asso pistons have 3mm removed from the inlet port side this then increases the inlet port timing which doesnít always make for an improvement especially on standard engines or cylinders previously tuned for the standard skirt length pistons. (The latest 2001 spec Asso pistons come with a full skirt at last!)
PROS: This kit was or still is considered to be the best kit on the market depending on whom you talk to. It uses an excellent strong piston with good rings. These pistons are ideal for Stage 3, 4, 5 or 6 tunes. The conversion fits onto a standard or race crankshaft with the standard length rod 107mm.
CONS: The piston is now ridiculously expensive compared to other pistons. There are limited oversizes 67 to 67.50mm. The rings tend to wear quite quickly and it is not uncommon for ring pegs to come out! The cylinder needs machining and an Indian cylinder head needs reworking to suit the kit. Once the cylinder is worn out then it could be scrap. MB Developments would offer either the Suzuki 205 piston conversion or the Polaris 220 piston conversion so all would not be lost!
PROS: This kit is excellent, the piston in genuine form is excellent, as is the Wiseco piston. There are a large amount of pistons available from 67 to 69mm, then the Polaris piston could be used. These pistons are cheaper than Honda MTX pistons. This kit could rectify worn out Honda 205 cylinders. This kit is ideal for Stage 2, 3, 4, 5 or 6 tunes.
CONS: The piston uses an 18mm gudgeon pin, MB Developments donít recommend piston bushes, but recommend the Vespa Ape rod conversion! With the rod conversion it is excellent and works in any type of crankshaft with a little work, this then makes the cylinder kit a top kit. The kit requires machining and a cylinder packing plate is required making the kit expensive short term, long term it is a cheap long lasting kit.
PROS: This kit is excellent with a large amount of rebores available from 68.5 to 70mm. These pistons are cheaper than Honda MTX pistons. This kit is ideal for Stage 4, 5 or 6 tunes.
CONS: This kit requires the con rod to be converted to a Yamaha 115mm putting an extra price on the kit. A small amount of machining is required.
PROS: This kit is excellent, the piston is excellent. There are an amount of pistons available from 69.75 to 70.75mm. These pistons are cheaper than Honda MTX pistons. This kit is ideal for Stage 2, 3, 4, 5 or 6 tunes. This kit could rectify worn out Honda 205 cylinders.
CONS: The piston uses an 18mm gudgeon pin, MB Developments donít recommend piston bushes, but recommend the Vespa Ape rod conversion! With the rod conversion it is excellent and works in any type of crankshaft with a little work, this in then makes the cylinder kit a top kit. On the last over size piston the bore gets a little on the thin side. The kit requires machining and a cylinder packing plate is required making the kit expensive short term, long term it is a cheap long lasting kit.
PROS: This piston is excellent and is available in various makes all been easy to get and are cheap in comparison to other pistons.
CONS: The piston uses an 18mm gudgeon pin, MB Developments donít recommend piston bushes, but recommend the Vespa Ape rod conversion! With the rod conversion it is excellent and works in any type of crankshaft with a little work, this in then makes the cylinder kit a top kit. On the last over size piston the bore gets a little on the thin side. The kit requires machining making the kit expensive short term, long term it is a cheap long lasting kit.
Other piston kits are available with combinations of standard 58mm or long stroke 60mm crankshafts. These kits listed have proved to be good reliable kits over the years and MB Developments are happy to list them.
CYLINDER KIT RECOMMENDATIONS
The above cylinder conversions have been explained quite thoroughly, today a lot of cylinders have been totally butchered or just worn out and there has been for a number of years a need for a replacement 200 cylinder.
There have been a few all ready mentioned, the Autisa, MDP, Indian, TS1 and now the Rapido.
We looked at what people actually wanted, most wanted a Scooter to have a cruising speed of approximately 70-mph with a top speed of 80ish, the scooter must be good for two up riding, touring, used daily for work or be a quick street racer.
It must be long lasting and at the same time be reasonably cheap to buy.
We are basically talking of a stage 4 or 5 tune, but like other dealers we found it very difficult to make up these kits whatever the piston used and keep them on stock waiting for the customer to turn up.
Tuning 100 cylinder kits a year is not that hard, but when the phone goes, customers call, delivery people call and your employees need you, work life gets very difficult!
For a cheap bolt on kit MB Developments have perfected the Indian cylinder conversion.
This conversion has proved popular over the years.
We have recommended this as it fits the criteria of most customers.
The Indian cylinder has been around since the early eighties.
The early ones were very rough mainly around the transfer feeds in to the cylinder, one transfer port was wider and higher than the other.
Over the last few years these cylinders have improved, the transfers are nearly the same, the cylinder has now been painted black and with the surfaces machined they look quite reasonable!
MB DEVELOPMENTS FACTORY STAGE 4 200 KIT
We use the Indian cylinder that is basically a stage 4 tune with a Vertex or Asso two-ring piston, the piston to bore clearance needs checking and sometimes honing out as cylinder and pistons alter in size.
Some port edges are checked and cleaned up.
We use a 200 Indian cylinder head, which is reprofiled, and the combustion chamber is altered to run on unleaded fuel.
Studs nuts and washers are fitted and correct gaskets supplied to suit the port sizes.
The complete MB Developments factory Stage 4 kit
Ready to bolt on.
MB Developments have again over the years looked at what customers want and to get the speed on a daily basis a larger carb is needed.
We have perfected the 30mm Dellorto PHBH carb kit to now include our special remote air filter.
This carb gives the horsepower and speed but our filter keeps the Scooter clean and quiet and the engine lasts much longer!
The carb comes as a complete kit, pre-jetted ready to go and compliments the factory stage 4 kit.
The factory kit can run on any exhaust.
For every day use we suggest the Clubman exhaust system which is again cheap and reliable and can reach 8000 rpm.
For quicker speeds any expansion can be used.
MB Developments have our own Devtour, which then makes the ultimate fast, rideable long lasting 200cc kit.
The difference in horsepower from a Clubman to a MBD Devtour could be up to 5 HP!
Our preferred exhaust system for touring tunes is the AF clubman.
We cannot buy the parts to make our Clubman exhausts at the price we retail these exhausts.
They give good performance up to 15 HP.
They fit well and look good.
They come epoxy coated black or grey.
We supply them with a chrome exhaust clamp and one of our exhaust gaskets.
This kit can run on any crankshaft, thatís your choice, but MBD strongly recommends changing the crankshaft for the latest race crankshaft and upgrade the bearings at the same time.
If not already done fit an electronic ignition.
FACTORY STAGE 4 200 UPDATE JAN 2003
From our point of view the factory 200 kit is a godsend, as we donít have to tune so many cylinders.
Saying this there are not enough old cylinders around that can be tuned anyway.
The Factory kit is very popular but not without its problems.
As mentioned the piston to bore clearance needs checking.
You can not presume a 66mm piston fits straight into a 66mm bore!
We do so many of these kits that we have run into some problems.
The bore alters in size from the factory, but by only a small amount.
The pistons originally used by us in this kit were the Vertex 2 ring type, these were ideal, their size sometimes gave perfect piston to bore clearance of that magic figure of .003íí occasionally a cylinder needed honing to suit a larger piston.
All was well until the pistons ran out of stock!
If a cylinder was over sized then an Autisa 2-ring piston was used because this was slightly larger and cured the problem of over bored cylinders from the factory.
But these pistons ran out and will never be replaced as the factory went bust.
With no Vertex or Autisa pistons we started to get Asso 2 ring pistons as now supplied with the Rapido tuned kit.
These came slightly undersized compared to the Vertex, apart from that they were identical.
The worse you can get is a clearance of .005íí which usually gives piston slap and rattles.
Not what we want to sell as a company!
To get over the important piston to bore clearance we have reintroduced the Vertex and Mahle 3 ring pistons, which are slightly larger in size making most cylinders usable.
OK they have cast iron rings but are standard fitment from the factory and as the exhaust port is not too wide they are reliable.
Basically the cylinder set up is the same as a standard Italian GP 200 (with increased port timings).
By using the Asso / Vertex piston with 3mm removed from the inlet side this gives an inlet timing of around 153 - 155 degrees, ideal for a stage five tune.
If using a standard length skirt the timing decreases to around 142 - 145 degrees, ideal for a MB stage 4 tune or a cylinder with a carb of 25 - 30mm.
OK, our recommended kit uses slightly larger inlet timing but always works showing there are no fixed rules.
Because these kits are so popular and people actually read our tuning spec information we feel we should say this.
THE TOTAL 200cc KIT
All parts are usually available separately or as a kit.
WE BELIEVE THIS KIT TO BE AN EXCELLENT COMPLETE BOLT ON PACKAGE!
IF REQUIRED EXTRA TUNING CAN BE DONE TO THE CYLINDER MAKING IT A FULL RACE SPEC STAGE 5.
See also TS1 page for an alternative more powerful 200cc kit
There have been over the years a number of differences between 200 cylinders. These differences have been very hard to keep track of. The main differences between cylinders regularly worked by MB Developments are listed.
Early GT / TV 200 cylinders have no cut out notches on the top fin.
There are 2 types; the early one has a very wide exhaust port, this is the most common type. The later type has a very small exhaust port width. Both cylinders have the lowest and largest inlet port compared to all other cylinders, these differences make the GT cylinder the easiest to identify.
When using a GT cylinder it becomes difficult to choose a piston for it. If using an original 3 ring type piston the piston is prone to drop rings after 2000miles. If using an Asso or Vertex piston with the cut down inlet shirt the inlet timing becomes to big even for race tuning.
It is also difficult to do the basic Honda 205 conversion because of the lowered inlet port.
SX 200 and GP 200 cylinders look the same, they both have 2 small cut outs on the top fin. These could be considered the same especially when using them for tuning. These both suit all pistons and all conversions.
Scooters India Limited have their own cylinder.
This cylinder has good and bad points. The bad points are the transfer ports are not level and are different sizes and the ports look rough in appearance.
Despite this the port timings are very close to a stage 4 tune, the cast iron used is very hard making them hard wearing and long lasting, The port sizes are much larger than an Italian cylinder making it impossible to do a standard, stage 1, 2 or 3 tune. By the time the ports are polished and transfers are matched the kit becomes a race spec stage 5.
There have been some other pattern cylinders available.
The Italian one has been coming through from MDP; it is copy of the early SX cylinder but is not machined correctly.
The transfer and exhaust heights are not tall enough and these go slower. These are made from very poor cast iron and can totally wear out in 100 miles on a full race tune.
Only use these for mild tunes with small exhaust ports.
The other pattern cylinder was made by Autisa and used by Spanish factory, these are also identified by having no cut outs on the top fin, but on the base gasket it has a lump cast into it. Put a base gasket in place and you will see this.
Some of these cylinders were soft and wore out quickly, some were hard and were very good. This is hard to tell unless tuning them. Both type cylinders had nice sized ports and worked well with all pistons, unfortunately these are hard to get now.
In the above list MB Developments recommends various types of pistons. These are used for their reliability of piston and ring and availability.
They are, when available are as follows;
Vertex, Asso, Borgo, Hepolite or Mahle 200cc pistons, avaiable sizes are; 66, 66.4, 66.6, 66.8, 67 and 67.4mm
Vertex 200 to 225cc pistons, available sizes are; 66, 66.4, 66.6, 66.8, 67, 67.2, 67.4, 70, 70.4, 70.6, and 70.8mm
Asso 200 to 225cc pistons, available sizes are; 66, 66.4, 66.6, 66.8, 67, 67.2, 67.4, 70, 70.4, 70.6, and 70.8mm
Honda 205cc pistons; 67, 67.25 and 67.5mm
Suzuki 205cc pistons genuine; 67, 67.5 and 68mm
Suzuki 205cc pistons Wiseco; 67, 67.5, 68, 68.5 and 69mm
Kawasaki 210cc pistons Wiseco; 68.5, 69, 69.5 and 70mm
Polaris 220cc pistons Wiseco 69.5, 70.25 and 70.75mm
Suzuki 225cc pistons Japanese 70, 70.5 and 71mm
Suzuki 225cc pistons Wiseco 70, 70.5 and 71mm
Other makes are available but MB Developments wouldnít choose to use them unless itís a last resort.
GPM, Meteor, Speed, Siam, Comec, Dinamin, these have 2 or 3 cast rings and should come in sizes of; 66, 66.2, 66.4, 66.6, 66.8, 67, 67.2 and 67.4mm.
Please E-mail us with any questions or comments.